Sheet transport apparatus, automatic document feeder, and image forming apparatus

ABSTRACT

A sheet transport apparatus is equipped with a sheet transport guide section for guiding a sheet to be transported. The sheet transport guide section includes a first transport guide member swingable about a first axis, and a second transport guide member swingable about a second axis, the second transport guide member forming a sheet transport path between the second transport guide member and the first transport guide member. The second transport guide member is arranged at a first position when the first transport guide member is closed, at a second position where the second transport guide member is opened from the first position when the first transport guide member is opened, or at a third position where the second transport guide member is opened from the second position.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119(a) toJapanese Patent Application No. 2015-083607 filed on Apr. 15, 2015, andJapanese Patent Application No. 2016-044689 filed on Mar. 8, 2016. Thecontents of these applications are incorporated herein by reference intheir entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet transport apparatus, anautomatic document feeder (ADF), and an image forming apparatus such asa copying machine, a multifunction printer (MFP) or the like.

2. Description of the Related Art

Generally, a sheet transport apparatus is equipped with a sheettransport guide section for guiding a sheet to be transported.

As such, a conventional sheet transport apparatus is equipped with asheet transport guide section including a first transport guide memberand a second transport guide member. The first transport guide member isswingable about a first axis extending in width directions of a sheet,the width directions being orthogonal or substantially orthogonal to asheet transport direction. The second transport guide member forms asheet transport path for allowing passage of a sheet between the secondtransporg guide member and the first transport guide member. The secondtransport guide member is fixed on a main body of the sheet transportapparatus by a fixing member such as a screw.

In this sheet transport apparatus in which the second transport guidemember is fixed on the main body of the sheet transport apparatus, whena sheet is jammed at the second transport guide member on a far side ofthe first transport guide member (namely, when a paper jam occurs), itis difficult to remove the sheet jammed at the second transport guidemember on the far side of the first transport guide member (namely, apaper jam clearing operation is troublesome).

In this regard, a document transport apparatus disclosed in PatentLiterature 1 is provided with an upper frame (a first transport guidemember) and an intermediate frame (a second transport guide member)which are supported by a single common shaft in an openable and closablemanner, and is also provided with a latch part for latching these framestogether.

[Patent Literature 1] JP 11-106086 A SUMMARY OF THE INVENTION Problemsto be Solved by the Invention

However, in the document transport apparatus disclosed in PatentLiterature 1, the upper frame (the first transport guide member) and theintermediate frame (the second transport guide member) are latchedtogether at the latch part. This structure prevents free opening/closingmovements of the intermediate frame (the second transport guide member)relative to the upper frame (the first transport guide member), andresults in poor work efficiency in the paper jam clearing operation fora document (a sheet).

In view of the situation, the present invention aims to provide a sheettransport apparatus, an automatic document feeder (ADF), and an imageforming apparatus, in which a second transport guide member can beopened and closed freely relative to a first transport guide member,thereby facilitating a paper jam clearing operation for a sheet andenhancing the work efficiency in a paper jam clearing operation.

In order to solve the above problem, the present invention providessheet a transport apparatus according to each of First and SecondEmbodiments, an automatic document feeder, and an image formingapparatus, as described below.

(1) Sheet Transport Apparatus

(1-1) Sheet Transport Apparatus According to First Embodiment

A sheet transport apparatus according to First Embodiment of the presentinvention is a sheet transport apparatus equipped with a sheet transportguide section for guiding a sheet to be transported, and has thefollowing characteristics. The sheet transport guide section includes afirst transport guide member which is swingable about a first axisextending in a width direction of the sheet, the width direction beingorthogonal or substantially orthogonal to a sheet transport direction,and a second transport guide member which is swingable about a secondaxis extending in the width direction and which forms a sheet transportpath for allowing passage of the sheet between the second transportguide member and the first transport guide member. The second transportguide member is arranged at a first position when the first transportguide member is closed, at a second position where the second transportguide member is opened from the first position when the first transportguide member is opened, or at a third position where the secondtransport guide member is opened from the second position.

(1-2) Sheet Transport Apparatus According to Second Embodiment

A sheet transport apparatus according to Second Embodiment of thepresent invention is a sheet transport apparatus equipped with a sheettransport guide section for guiding a sheet to be transported, and hasthe following characteristics. The sheet transport guide sectionincludes a first transport guide member which is swingable about a firstaxis extending in a width direction of the sheet, the width directionbeing orthogonal or substantially orthogonal to a sheet transportdirection, a second transport guide member which is swingable about asecond axis extending in the width direction and which forms a sheettransport path for allowing passage of the sheet between the secondtransport guide member and the first transport guide member, and aswingable member which is swingable about a third axis extending in thewidth direction, relative to the first transport guide member, at adifferent position from the first axis of the first transport guidemember. When the first transport guide member is opened or closed, thefirst transport guide member moves in an opening or closing directionabout the first axis, followed by a swinging movement of the swingablemember about the third axis, and the second transport guide member iscaused to swing about the second axis in synchronization with theswinging movement of the swingable member.

(2) Automatic Document Feeder

An automatic document feeder according to the present invention isequipped with the sheet transport apparatus according to First or SecondEmbodiment of the present invention as de scribed above.

(3) Image Forming Apparatus

An image forming apparatus according to the present invention isequipped with the automatic document feeder according to the presentinvention as described above,

In an example of Second Embodiment described above, even when the secondtransport guide member is opened or closed, the first transport guidemember and the swingable member are arranged not to swing insynchronization with an opening or closing movement of the secondtransport guide member about the second swing axis.

In another example of Second Embodiment described above, the swingablemember includes a reciprocating part which makes a reciprocatingmovement in reciprocating directions which are orthogonal orsubstantially orthogonal to the width direction when the swingablemember swings about the third axis in synchronization with an openingmovement of the first transport guide member, and also includes anabutting part provided on the reciprocating part and arranged to abut onthe second transport guide member. In addition, the second transportguide member includes a sliding contact guide part which is arranged tocome into sliding contact with the abutting part of the swingable memberwhen the reciprocating part of the swingable member moves, and therebyto cause the second transport guide member to be lifted about the secondaxis.

In yet another example of Second Embodiment described above, theswingable member further includes a supporting part, and the abuttingpart is supported by the reciprocating part by means of the supportingpart.

In still another example of Second Embodiment described above, thesupporting part is flexible.

In a further example of Second Embodiment described above, the sheettransport apparatus further includes a frame provided in a main body ofthe sheet transport apparatus. The frame is provided with a guide partfor guiding the reciprocating part of the swingable member in thereciprocating directions. The reciprocating part of the swingable memberis provided with an engagement portion to be engaged with the guide partof the frame.

In a yet further example of Second Embodiment described above, the sheettransport apparatus further includes a biasing member which is providedbetween the reciprocating part of the swingable member and the frame,and which biases, by means of the swingable member, the first transportguide member in an open direction about the first axis.

In a still further example of Second Embodiment described above, thesecond transport guide member is arranged at a first position when thefirst transport guide member is closed, at a second position where thesecond transport guide member is opened from the first position when thefirst transport guide member is opened, or at a third position where thesecond transport guide member is opened from the second position.

In an example of First and Second Embodiments described above, thesecond transport guide member stops at the third position.

In another example of First and Second Embodiments described above, adifference between a degree of opening of the second transport guidemember at the second position and a degree of opening of the secondtransport guide member at the third position is greater than adifference between a degree of opening of the second transport guidemember at the second position and a degree of opening of the secondtransport guide member at the first position.

In yet another example of First and Second Embodiments described above,the sheet transport apparatus further includes a third transport guidemember for guiding the sheet to be transported between the thirdtransport guide member and the second transport guide member. An openingbetween the second transport guide member at the third position and thethird transport guide member is wider than an opening between the secondtransport guide member at the third position and the first transportguide member in an open state.

In still another example of First and Second Embodiments describedabove, when the second transport guide member is opened, the secondtransport guide member stops at the third position where a center ofgravity of the second transport guide member is on a closed side of thesecond transport guide member relative to an imaginary vertical linewhich passes through the second axis.

In a further example of First and Second Embodiments described above,when the second transport guide member is opened, the second transportguide member is limited by the first transport guide member and stops atthe third position where a center of gravity of the second transportguide member is on an open side of the second transport guide memberrelative to an imaginary vertical line which passes through the secondaxis.

In a yet further example of First and Second Embodiments describedabove, when the first transport guide member is opened, the firsttransport guide member stops at a first position thereof where a centerof gravity of the first transport guide member is on a closed side ofthe first transport guide member relative to an imaginary vertical linewhich passes through the first axis.

In a still further example of First and Second Embodiments describedabove, when the first transport guide member is opened, the firsttransport guide member stops at a second position thereof where a centerof gravity of the first transport guide member is on an open side of thefirst transport guide member relative to an imaginary vertical linewhich passes through the first axis.

In a different example of First and Second Embodiments described above,a recess is provided at an end of the second transport guide memberopposite to a swing fulcrum of the second transport guide member.

In a yet different example of First and Second Embodiments describedabove, a recess is provided in the second transport guide member, on anoperation side relative to a center in the width direction.

In a further different example of First and Second Embodiments describedabove, the sheet transport apparatus further includes an interlockdetection switch for prohibiting an action of the apparatus, and anactivating part for activating the interlock detection switch. Theinterlock detection switch is provided in either of the first transportguide member or the second transport guide member, and the activatingpart is provided in the other transport guide member. The interlockdetection switch and the activating part are positioned such that, in astate where the first transport guide member is closed, the interlockdetection switch is turned on by the activating part. The first axis inthe first transport guide member and the second axis in the secondtransport guide member are provided at different positions from eachother.

According to the present invention, the second transport guide membercan be opened and closed freely relative to the first transport guidemember, thereby facilitating a paper jam clearing operation for a sheetand enhancing the work efficiency in the paper jam clearing operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing a schematic configuration of an imageforming apparatus according to the embodiments of the present invention.

FIG. 2 is a schematic front view schematically showing a generalconfiguration of an image reading apparatus shown in FIG. 1, with afirst transport guide member closed and a second transport guide memberat a first position.

FIG. 3 is a perspective view of an example of an automatic documentfeeder in the image reading apparatus shown in FIG. 2, with the firsttransport guide member open and the second transport guide member at asecond position.

FIG. 4 is a schematic front view of an example of the automatic documentfeeder in the image reading apparatus shown in FIG. 2, showing a sheettransport part on an enlarged scale.

FIG. 5 is a schematic front view similar to FIG. 4, with a frame, aswingable member, and a biasing member removed.

FIG. 6 is a perspective view of the automatic document feeder in theimage reading apparatus shown in FIG. 4, with the first transport guidemember closed.

FIG. 7 is a perspective view of the automatic document feeder in theimage reading apparatus shown in FIG. 4, with the first transport guidemember open.

FIG. 8 is a partial perspective view of the automatic document feedershown in FIG. 4, showing the first transport guide member, the secondtransport guide member, the swingable member, and the biasing member.

FIG. 9 is a schematic front view of a sheet transport part in theautomatic document feeder shown in FIG. 4, with the first transportguide member in the process of opening or closing by an opening/closingoperation by an operator, which causes the second transport guide memberto move rotationally between the first position and the second position.

FIG. 10 is a schematic front view of the sheet transport part of theautomatic document feeder shown in FIG. 4, with the first transportguide member fully open, which causes the second transport guide memberto be at the second position.

FIG. 11 is a schematic front view of the sheet transport part of theautomatic document feeder shown in FIG. 4, with the first transportguide member fully open, wherein the second transport guide member isbrought to a third position by an opening operation by an operator.

FIG. 12 is a perspective view of the second transport guide member, theswingable member, and the biasing member, extracted from the automaticdocument feeder.

FIGS. 13(a)-13(f) represent a general configuration of the swingablemember in the automatic document feeder, respectively being a back view,a plan view, a front view, a bottom view, a left side view, and a rightside view of the swingable member.

FIGS. 14(a) and 14(b) are front perspective views of the swingablemember in the automatic document feeder, as seen from top right and fromtop left, respectively.

FIG. 15 is a schematic sectional view showing an example of anengagement arrangement by which the second transport guide member isengaged with an automatic document feeder main body by fit engagementwhen the second transport guide member stops at its third position,wherein an exemplary dent in the second transport guide member isengaged with an exemplary stud in the automatic document feeder mainbody.

FIG. 16 is a schematic sectional view showing an example of anengagement arrangement by which the second transport guide member isengaged with an automatic document feeder main body by fit engagementwhen the second transport guide member stops at its third position,wherein an exemplary stud in the second transport guide member isengaged with an exemplary dent in the automatic document feeder mainbody.

FIG. 17 is an enlarged schematic front view of another example of thesheet transport part in the automatic document feeder of the imagereading apparatus shown in FIG. 2, with the first transport guide memberclosed and the second transport guide member at the first position.

FIG. 18 is a schematic front view of the sheet transport part in theautomatic document feeder shown in FIG. 17, with the first transportguide member in the process of opening or closing by an opening/closingoperation by an operator, which causes the second transport guide memberto move rotationally between the first position and the second position.

FIG. 19 is a schematic front view of the sheet transport part of theautomatic document feeder shown in FIG. 17, with the first transportguide member fully open, which causes the second transport guide memberto be at the second position.

FIG. 20 is a schematic front view of the sheet transport part of theautomatic document feeder shown in FIG. 17, with the first transportguide member fully open, wherein the second transport guide member isbrought to a third position by an opening operation by an operator.

FIG. 21 is a side perspective view of an interlock detection switch andan activating part for explaining their operation, with the firsttransport guide member fully open and the second transport guide memberin the process of opening or closing.

FIG. 22 is a schematic front view representing a positional relationshipbetween the interlock detection switch and the activating part, forexplaining their operation, with the first transport guide member andthe second transport guide member fully open.

FIG. 23 is a top, side perspective view of a part around a branchingmember, for explaining through-windows provided in the branching member,with the first transport guide member fully open and the secondtransport guide member removed.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments according to the present invention aredescribed with reference to the drawings.

[Image Forming Apparatus]

FIG. 1 is a front view showing a schematic configuration of an imageforming apparatus 100 according to the embodiments of the presentinvention.

As shown in FIG. 1, the image forming apparatus 100 includes an imagereading apparatus 200 and an image forming apparatus main body 110.Based on image data read by the image reading apparatus 200 or sent froman external device, the image forming apparatus main body 110 forms amonochrome image or a color image on a recording sheet P such asrecording paper.

The image reading apparatus 200 includes an automatic document feeder(ADF) 300 and a document reader 400. The document reader 400 scans adocument G (an example of the sheet) transported by the automaticdocument feeder 300 or a document G set on a platen 410. The documentreader 400 then outputs a scanned image of the document G as image data.

The image forming apparatus 100 is an electrophotographic image formingapparatus, and is a so-called tandem-method color image formingapparatus in which a plurality of image carriers (specifically,photoreceptors) are arranged side by side in a predetermined direction(in this example, in crosswise directions Y, i.e. left-right directionsin the drawings). In this example, the image forming apparatus 100 is acolor multifunction printer capable of forming a full-color image andoperated by the intermediate transfer method. The image formingapparatus 100 is not limited to a tandem-method color image formingapparatus as used in the present embodiments, and may be a color imageforming apparatus operated by other methods. Additionally, the imageforming apparatus 100 is not limited to a color image forming apparatusand may be a monochrome image forming apparatus.

The image forming apparatus main body 110 includes photoreceptors 11(specifically, photosensitive drums), static eliminators 12, chargers 13as charging units, an exposure unit 14, developing units 15, anintermediate transfer belt unit 16 as a primary transfer unit, drumcleaning units 17, a secondary transfer unit 18, a belt cleaning unit19, a fixing unit 20, a transport path R1, a paper feed tray 31, and adischarge tray 32.

In this image forming apparatus main body 110, surfaces of thephotoreceptors 11 are electrostatically charged by the chargers 13, andthe electrostatically charged areas are exposed to form electrostaticlatent images by the exposure unit 14. The electrostatic latent imagesare visualized (developed) as toner images by the developing units 15.The visualized toner images are electrostatically transferred on theintermediate transfer belt unit 16. The toner images transferred on theintermediate transfer belt unit 16 are transferred onto the recordingsheet P by the secondary transfer unit 18, and fixed thereon by thefixing unit 20.

A color image is composed of toner images in black (K), cyan (C),magenta (M), and yellow (Y) overlapped on each other. For this purpose,a set of the photoreceptor 11, the static eliminator 12, the charger 13,the developing unit 15, and the drum cleaning unit 17 is required foreach color. In this example, four such sets are provided to form tonerimages in four colors corresponding to black, cyan, magenta and yellow,and constitute four imaging stations Pa, Pb, Pc, and Pd, respectively.

In the imaging stations Pa, Pb, Pc, Pd, following operations areconducted.

The static eliminators 12-12 irradiate surfaces of the photoreceptors11-11 which are driven to rotate in a rotation direction B (clockwise inthe example shown in FIG. 1), thereby to remove (neutralize) electriccharges (residual charges) on the surfaces of the photoreceptors 11-11.

The chargers 13-13 charge the surfaces of the photoreceptors 11-11 whichare neutralized by the static eliminators 12-12, uniformly at apredetermined potential.

The exposure unit 14 exposes the surfaces of the photoreceptors 11-11which are uniformly charged by the chargers 13-13, and formselectrostatic latent images on the surfaces of the photoreceptors 11-11.

The developing units 15-15 develop the electrostatic latent imagesformed on the surfaces of the photoreceptors 11-11 by the exposure unit14, and form single-color toner images in corresponding colors on thesurfaces of the photoreceptors 11-11.

In the imaging stations Pa, Pb, Pc, Pd, toner images in correspondingcolors are formed on the surfaces of the photoreceptors 11-11 by aseries of above-mentioned operations.

The intermediate transfer belt unit 16 has primary transfer rollers 16 aand an intermediate transfer belt 16 b. To form four single-color tonerimages, four primary transfer rollers 16 a are provided on an inner sideof the intermediate transfer belt 16 b. By the primary transfer rollers16 a-16 a, the single-color toner images formed on the surfaces of thephotoreceptors 11-11 are transferred on the intermediate transfer belt16 b which circles in the direction of Arrow C.

The drum cleaning units 17-17 remove and collect residual toner whichwas not transferred onto the intermediate transfer belt 16 b and whichremains on the surfaces of the photoreceptors 11-11.

The secondary transfer unit 18 has a secondary transfer roller 18 a,which forms a nip region between the secondary transfer roller 18 a andthe intermediate transfer belt 16 b. The secondary transfer roller 18 aguides a recording sheet P conveyed in the transport path R1 into thenip region. While the recording sheet P passes the nip region, the tonerimages (for example, color toner images) formed on the surface of theintermediate transfer belt 16 b are transferred by the secondarytransfer roller 18 a onto the recording sheet P.

The belt cleaning unit 19 removes and collects residual toner which wasnot transferred onto the recording sheet P and which remains on thesurface of the intermediate transfer belt 16 b.

The fixing unit 20 has a heating roller 21 and a pressure roller 22.While the recording sheet P on which the toner images are transferredpasses between the heating roller 21 and the pressure roller 22, theheating roller 21 and the pressure roller 22 apply heat and pressure tothe recording sheet P, thereby fixing the toner images on the recordingsheet P.

A paper feed tray 31 is designed to accommodate recording sheets P.Pick-up rollers 33 are provided on a recording sheet P supply side ofthe paper feed tray 31. The pick-up rollers 33 draw a recording sheet Pfrom the paper feed tray 31 and guide the recording sheet P into thetransport path R1.

The recording sheet P is conveyed in the transport path R1, via thesecondary transfer unit 18 and the fixing unit 20, to discharge rollers36. The discharge rollers 36 are provided on a recording sheet Pdischarging side in the transport path R1. The discharge rollers 36discharge the recording sheet P transported in the transport path R1 toa discharge tray 32. A pair of registration rollers 34 and pairs oftransport rollers 35-35 are provided in the transport path R1. The pairof registration rollers 34 temporarily stops the recording sheet P so asto align a leading edge of the recording sheet P, and thereafter feedsthe recording sheet P in synchronization with the timing of transferringthe toner images at the nip region between the intermediate transferbelt 16 b and the secondary transfer roller 18 a. The pairs of transportrollers 35-35 assist the transport of the recording sheet P.

The transport path R1 includes a reverse path Rr. In the case where theimage forming apparatus main body 110 forms an image not only on a frontside of the recording sheet P but also on a back side thereof, therecording sheet P is transported backward from the discharge rollers 36to the reverse path Rr, thereby reversing the recording sheet P from oneside to the other, and guiding the reversed recording sheet P to thepair of registration rollers 34 again. Then, toner images are fixed onthe back side of the recording sheet P in the same manner as on thefront side, and the recording sheet P is discharged to the dischargetray 32.

In FIG. 1, the symbol X represents width directions (depth directions);the symbol Y represents crosswise directions (left-right directions)orthogonal to the width directions X; and the symbol Z represents heightdirections (specifically, vertical directions). Other membersillustrated in FIG. 1 with reference numerals/symbols but not describedabove will be described later.

[Overall Configuration of the Image Reading Apparatus]

FIG. 2 is a schematic front view schematically showing a generalconfiguration of the image reading apparatus 200 shown in FIG. 1, with afirst transport guide member 310 closed and a second transport guidemember 320 at a first position.

The image reading apparatus 200 shown in FIGS. 1 and 2 is an imagereading apparatus having a reduction optical system. The image readingapparatus 200 is configured to scan an image of a fixed document G in astationary original exposure mode and also to scan an image of a movingdocument G in a moving original exposure mode. In other words, the imagereading apparatus 200 includes an arrangement for scanning a fixeddocument and an arrangement for scanning a moving document.

To scan an image in a stationary original exposure mode, a document G isset on a platen glass 411 (see FIG. 2) which constitutes the platen 410,and is irradiated through the platen glass 411 by a light source unit420 which serves as an irradiation device. While the light source unit420 is moving from one side to the other in sub-scanning directions (thecrosswise directions Y) and irradiating the stationary document G, thelight source unit 420 receives reflected light from the irradiateddocument G in main scanning directions (the width directions X) whichare orthogonal to the sub-scanning directions.

To scan an image in a moving original exposure mode, a document G istransported in a transport direction Y1 by the automatic document feeder300 over a document reading glass 412 (see FIG. 2) which constitutes theplaten 410. While the light source unit 420 stays at a fixed position V(see FIG. 2) in the document reader 400 and irradiates the movingdocument G through the document reading glass 412, the light source unit420 receives reflected light from the irradiated document G in the mainscanning directions (the width directions X).

To be more specific, the document reader 400 includes not only theplaten glass 411, the document reading glass 412 and the light sourceunit 420, but also an optical system driving unit (not shown) for movingthe light source unit 420, a mirror unit 430, a condensing lens 440, anda photoelectric transducer (a CCD in this example) 450. These membersare accommodated in a frame body 400 a (see FIG. 2). As shown in FIG. 2,the light source unit 420 contains light sources 421 for emitting lightto a document G, and a first mirror 422 for guiding reflected light fromthe document G to the mirror unit 430.

The platen glass 411 and the document reading glass 412, each made of atransparent glass plate, have their ends in the main scanning directions(the width directions X) held on the frame body 400 a. The automaticdocument feeder 300 can be opened and closed relative to the documentreader 400 about an axis extending in the sub-scanning directions(crosswise directions Y) (for example, axially held by a hinge). Abottom face of the automatic document feeder 300 serves as a documenthold-down member for holding down the document G placed on the platenglass 411 of the document reader 400.

The mirror unit 430 contains, as shown in FIG. 2, a second mirror 431, athird mirror 432, and a support member (not shown). The support memberin the mirror unit 430 holds the second mirror 431 such that the secondmirror 431 can receive light from the first mirror 422 in the lightsource unit 420 and reflect the light to the third mirror 432. Thesupport member in the mirror unit 430 also holds the third mirror 432such that the third mirror 432 can receive the light from the secondmirror 431 and reflect the light to the condensing lens 440. Thecondensing lens 440 condenses the light from the third mirror 432 in themirror unit 430 into a light-receiving surface 451 of the photoelectrictransducer 450. The photoelectric transducer 450 converts the light fromthe condensing lens 440 (document image light) into an electric signalas image data.

The optical system driving unit in the document reader 400 is configuredto move the light source unit 420 in the sub-scanning directions (thecrosswise directions Y) at a constant speed, and to move the mirror unit430 also in the sub-scanning directions (the crosswise directions Y) ata speed half as fast as the speed of the light source unit 420.

The sheet transport apparatus according to the present embodiments isapplied to the automatic document feeder 300. The automatic documentfeeder 300 includes a document tray 301 for holding a document G to betransported, a discharge tray 302 provided under the document tray 301,a main transport path 303 connecting these trays, a pair of upstreamtransport rollers 304, and a pair of downstream transport rollers 305.

The pair of upstream transport rollers 304 is provided upstream of thedocument reading glass 412 in the transport direction Y1 of the documentG, and transports the document G from an upstream side to the documentreading glass 412. The pair of downstream transport rollers 305 isprovided downstream of the document reading glass 412 in the transportdirection Y1, and transports the document G to a downstream side fromthe document reading glass 412. Namely, the pair of upstream transportrollers 304, the document reading glass 412, and the pair of downstreamtransport rollers 305 are arranged in this order in the main transportpath 303. The document reading glass 412 is arranged in a substantiallyhorizontal manner so as to form a part of a guide wall of a reversesheet transport path 303 b (see FIG. 2) which constitutes the maintransport path 303.

Other members illustrated in FIG. 2 with reference numerals/symbols butnot described above will be described later.

FIG. 3 is a perspective view of an example of the automatic documentfeeder 300 in the image reading apparatus 200 shown in FIG. 2, with thefirst transport guide member 310 open and the second transport guidemember 320 at a second position. In FIG. 3, the automatic documentfeeder is illustrated with a front cover removed.

FIG. 4 is a schematic front view of an example of the automatic documentfeeder 300 in the image reading apparatus 200 shown in FIG. 2, showing asheet transport part on an enlarged scale. FIG. 5 is a schematic frontview similar to FIG. 4, with a frame FL, a swingable member 330, and abiasing member 340 removed.

The automatic document feeder 300 is equipped with a sheet transportguide section 306 for guiding a document G to be transported.

The sheet transport guide section 306 has a first transport guide member310 and a second transport guide member 320.

The first transport guide member 310 is swingable about a first axis P1(see FIGS. 4 and 5) which extends in the width directions X of thedocument G, the width directions X being orthogonal or substantiallyorthogonal to the transport direction Y1 of the document G.

To be more specific, the first transport guide member 310 is swingablyarranged on a first swing axis 310 a (see FIGS. 2, 4, and 5) whichextends in the width directions X. In this example, the first swing axis310 a is fixed on the automatic document feeder main body 300 a (anexample of the sheet transport apparatus main body) (see FIGS. 3-5).

When the first transport guide member 310 is closed, the secondtransport guide member 320 is covered by the first transport guidemember 310 and forms a first sheet transport path 303 a (an example ofthe sheet transport path) for allowing passage of a document G betweenthe second transport guide member 320 and the first transport guidemember 310 (see FIGS. 2, 4, and 5). The second transport guide member320 is swingable about a second axis P2 which extends in the widthdirections X (see FIGS. 4 and 5).

To be more specific, the second transport guide member 320 is swingablyarranged on a second swing axis 320 a (see FIGS. 2, 4, and 5) whichextends in the width directions X. In this example, the pair of upstreamtransport rollers 304, composed of a first registration roller 304 a anda second registration roller 304 b (see FIGS. 4 and 5), temporarilystops a document G transported in the first sheet transport path 303 aand resumes the transport of the document G at a predetermined timing.The first registration roller 304 a is provided in the first transportguide member 310, and the second registration roller 304 b is providedin the automatic document feeder main body 300 a. The second swing axis320 a serves as the axis of rotation for the second registration roller304 b provided in the automatic document feeder main body 300 a. Namely,the second transport guide member 320 is swingably provided on the axisof rotation of the second registration roller 304 b (the second swingaxis 320 a).

The second transport guide member 320 is detachably provided on the axisof rotation of a roller, which in this example is the axis of rotationof the second registration roller 304 b (the second swing axis 320 a).Specifically, the second transport guide member 320 has a latch portion320 d (see FIGS. 4 and 5) to be latched on the second swing axis 320 a.The latch portion 320 d of the second transport guide member 320 is madeof a flexible member such as a resin, and has a shape of the letter Cwhich embraces the second swing axis 320 a and whose opening is smallerthan the diameter of the second swing axis 320 a. The C-shaped latchportion 320 d of the second transport guide member 320 can be removablyfitted around the second swing axis 320 a. Thus, the second transportguide member 320 can be arranged swingably around and detachably on thesecond swing axis 320 a.

The automatic document feeder 300 is further equipped with a pick-uproller 311 (see FIGS. 1, 2, 4, and 5), a retard roller 312 (see FIGS. 1,2, 4, and 5), and a separation member such as a separation roller or aseparation pad (a separation roller 324 in this example).

The pick-up roller 311 and the retard roller 312 are provided in thefirst transport guide member 310. The pick-up roller 311 picks up adocument G on the document tray 301 and feeds the document G in thetransport direction Y1 from the document tray 301 to the first sheettransport path 303 a. The retard roller 312, provided downstream of thepick-up roller 311 in the transport direction Y1, catches the document Gconveyed by the pick-up roller 311 between the retard roller 312 and theseparation roller 324 and transports the document G further downstreamin the transport direction Y1.

The separation roller 324 is provided in the second transport guidemember 320. With the separation roller 324 and the retard roller 312being face to face with each other, the separation roller 324 separatesone document G from another (to separate overlapping documents G) whileone or more documents G are transported between the separation roller324 and the retard roller 312.

In the thus configured automatic document feeder 300, the pick-up roller311 feeds a document G in between the retard roller 312 and theseparation roller 324, where overlapped documents G are separated fromone another, and the rotationally driven retard roller 312 transportsone document G after another. The document G transported by the retardroller 312 is guided into the first sheet transport path 303 a and fed,one by one, between the pair of upstream transport rollers 304.

To be more specific, the pick-up roller 311 is capable of moving to andfrom a document G held on the document tray 301, by means of a pick-uproller driving unit (not shown). The pick-up roller 311 is connectedwith the retard roller 312 by a drive transmission means 313 includingan endless belt and the like (see FIGS. 1, 2, 4, and 5), in such amanner as to rotate in the same direction as the retard roller 312. Onreceiving a request for scanning a document G, the pick-up roller 311and the retard roller 312 are rotationally driven by a document feederdriving unit (not shown) in a rotation direction W (see FIG. 2) fortransporting the document G in the transport direction Y1.

In this example, the automatic document feeder 300 is configured totransport a document G for scanning of one side (the front side), thento reverse the document G from one side to the other, and to transportthe document G for scanning of the other side (the back side).

To be more specific, the sheet transport guide section 306 is configuredto reverse a document G from one side to the other. The first transportguide member 310 has a first sheet guide surface 310 b (see FIGS. 3-5)which faces one side (the front side) of the document G before reversal.The second transport guide member 320 has a second sheet guide surface320 b (see FIGS. 3-5) which faces the other side (the back side) of thedocument G before reversal, and a third sheet guide surface 320 c (seeFIGS. 4 and 5) which faces the other side (the back side) of thereversed document G.

The automatic document feeder 300 further includes a reverse sheettransport path 303 b (see FIGS. 2, 4, and 5), a discharge transport part307 (see FIGS. 1, 2, 4, and 5), and a third transport guide member 350(see FIGS. 1, 2, 4, and 5).

The reverse sheet transport path 303 b is arranged to reverse a documentG from one side to the other while allowing passage of the document Gconveyed from the first sheet transport path 303 a. The main transportpath 303 is composed of the first sheet transport path 303 a and thereverse sheet transport path 303 b.

To be more specific, the main transport path 303 is formed like a loopin which a document G is guided from the retard roller 312, through thepair of upstream transport rollers 304, the document reading glass 412,and the pair of downstream transport rollers 305, to the dischargetransport part 307.

As shown in FIGS. 4 and 5, the automatic document feeder 300 is furtherequipped with an upstream guide 3031, a downstream guide 3032, and adocument reading guide 3033, in the automatic document feeder main body300 a. The document reading guide 3033 is disposed above the documentreading glass 412. The upstream guide 3031 and the downstream guide 3032are disposed below the pair of upstream transport rollers 304 and thepair of downstream transport rollers 305, respectively.

To be more specific, the position of the upstream guide 3031 isdownstream of the pair of upstream transport rollers 304 and upstream ofthe document reading glass 412 in the transport direction Y1. Theposition of the downstream guide 3032 is downstream of the documentreading glass 412 and upstream of the pair of downstream transportrollers 305 in the transport direction Y1. The document reading guide3033 faces the upstream guide 3031, the downstream guide 3032, and thedocument reading glass 412, with a predetermined gap therebetween. Thereverse sheet transport path 303 b is defined between a guide wallcomposed of the upstream guide 3031, the document reading glass 412 andthe downstream guide 3032 and another guide wall composed of thedocument reading guide 3033.

At the discharge transport part 307, a document G which has beenreversed from one side to the other in the reverse sheet transport path303 b is either discharged to the outside or transported backward duringa discharging action.

To be more specific, the discharge transport part 307 includes a sheetdischarge transport path 307 a (see FIGS. 2, 4, and 5), a pair ofdischarge rollers 307 b (see FIGS. 2, 4, and 5), a sheet guide unit 307c (see FIGS. 4 and 5) which forms the sheet discharge transport path 307a between the sheet guide unit 307 c and a bottom surface of thedocument tray 301, and a discharge roller driving unit (not shown) whichrotationally drives the pair of discharge rollers 307 b.

The sheet discharge transport path 307 a is configured to guide adocument G transported through the reverse sheet transport path 303 b tothe discharge tray 302.

The pair of discharge rollers 307 b is provided downstream of the pairof downstream transport rollers 305 in the transport direction Y1,specifically between the pair of downstream transport rollers 305 andthe discharge tray 302. The pair of discharge rollers 307 b not onlytransports a document G conveyed from the pair of downstream transportrollers 305 to the discharge tray 302, but also transports a document Gconveyed from the pair of downstream transport rollers 305 backward in areverse transport direction Y2 which is an opposite direction of thetransport direction Y1 such that a trailing end of the document G (anupstream end in the transport direction Y1) serves as a leading end inthe backward travel (see FIGS. 4 and 5).

The discharge roller driving unit is configured to transport a documentG in the transport direction Y1 by driving the pair of discharge rollers307 b to rotate in a forward direction, or to transport (to switch back)a document G in the reverse transport direction Y2 by driving the pairof discharge rollers 307 b to rotate in a reverse direction.

The third transport guide member 350 is provided (fixed) in theautomatic document feeder main body 300 a. When the second transportguide member 320 is closed, the third transport guide member 350 iscovered by the second transport guide member 320 and forms a secondsheet transport path 303 c (see FIGS. 2, 4, and 5) between the thirdtransport guide member 350 and the second transport guide member 320.The second sheet transport path 303 c allows passage of the document Gwhich is transported backward at the discharge transport part 307. Thethird transport guide member 350 has a fourth sheet guide surface 350 b(see FIGS. 4 and 5) which faces one side (the front side) of thereversed document G.

The first sheet guide surface 310 b in the first transport guide member310 and the second sheet guide surface 320 b in the second transportguide member 320 constitute the first sheet transport path 303 a. Thethird sheet guide surface 320 c in the second transport guide member 320and the fourth sheet guide surface 350 b in the third transport guidemember 350 constitute the second sheet transport path 303 c.

In this example, the automatic document feeder 300 further includes abranching member 308 (see FIGS. 1, 2, 4, and 5).

To be more specific about this automatic document feeder 300, the thirdtransport guide member 350 and the branching member 308 are disposedunder the second transport guide member 320, and the pair of downstreamtransport rollers 305 and the document reading guide 3033 are disposedunder the third transport guide member 350 and the branching member 308.

The branching member 308 is disposed between an exit of the reversesheet transport path 303 b and an entry of the second sheet transportpath 303 c.

To be more specific, the branching member 308 is disposed at a branchinto a passage from the reverse sheet transport path 303 b to the sheetdischarge transport path 307 a and a passage from the sheet dischargetransport path 307 a to the second sheet transport path 303 c. When thesecond transport guide member 320 is closed and covers the branchingmember 308, the branching member 308 guides a document G from the exitof the reverse sheet transport path 303 b toward the discharge transportpart 307 or guides a document G which is transported backward at thedischarge transport part 307 toward the entry of the second sheettransport path 303 c.

The sheet discharge transport path 307 a serves not only as a forwardtransport path for a document G which is transported by forward rotationof the pair of discharge rollers 307 b but also as a reverse transportpath for a document G which is transported by reverse rotation of thepair of discharge rollers 307 b.

After a document G is transported backward by the pair of dischargerollers 307 b such that the trailing end of the document G serves as aleading end in the backward travel, the document G is guided by thebranching member 308 into the second sheet transport path 303 c. Thesecond sheet transport path 303 c guides the document G into the firstsheet transport path 303 a, on an upstream side of the pair of upstreamtransport rollers 304 in the transport direction Y1.

The branching member 308 is rotatable about a rotation axis extending inthe width directions X of the document G, the width directions X beingorthogonal or substantially orthogonal to the transport direction Y1 ofthe document G.

To be more specific, the branching member 308 is rotatably provided on arotation axis 350 a (see FIGS. 2, 4, and 5) extending in the widthdirections X. The pair of downstream transport rollers 305, composed ofa first transport roller 305 a and a second transport roller 305 b (seeFIGS. 4 and 5), is provided in the automatic document feeder main body300 a. The first transport roller 305 a is disposed on an outer side ofthe loop-like main transport path 303, and the second transport roller305 b is disposed on an inner side of the loop-like main transport path303. In this example, the rotation axis 350 a is the axis of rotation ofthe second (inner) transport roller 305 b provided in the automaticdocument feeder main body 300 a. In other words, the branching member308 is rotatably arranged on the rotation axis 350 a of the secondtransport roller 305 b.

Specifically, the branching member 308 has a substantially triangularshape in front view. The branching member 308 includes a C-shaped part308 a (see FIGS. 4 and 5) to be arranged on the rotation axis 350 a. TheC-shaped part 308 a of the branching member 308 embraces the rotationaxis 350 a, and slidably rests on the outer circumferential surface ofthe rotation axis 350 a. Owing to this arrangement, the branching member308 allows the C-shaped part 308 a to be rotatably engaged with therotation axis 350 a. Therefore, the branching member 308 can be arrangedon the rotation axis 350 a rotatably about the rotation axis 350 a.

The branching member 308 is arranged to take either a first attitude (asshown in FIGS. 1, 2, 4 and 5) for guiding a document G from the sheetdischarge transport path 307 a to the second sheet transport path 303 cor a second attitude for guiding a document G from the reverse sheettransport path 303 b to the sheet discharge transport path 307 a.

In this example, the branching member 308 blocks a path between thereverse sheet transport path 303 b and the sheet discharge transportpath 307 a by its own weight, and opens a path between the sheetdischarge transport path 307 a and the second sheet transport path 303 cby its own weight. To be more specific, a claw 308 b (a tip end) of thebranching member 308 (see FIGS. 4 and 5) normally abuts against thesheet guide unit 307 c. When the leading end (the downstream end in thetransport direction Y1) of the document G travels from the reverse sheettransport path 303 b to the sheet discharge transport path 307 a, theclaw 308 b is lifted upwardly about the rotation axis 350 a by a forceof transporting the document G, so that the branching member 308 takesthe second attitude and permits the document G to be transported to thesheet discharge transport path 307 a. After the trailing end of thedocument G passes the branching member 308, the claw 308 b fallsdownwardly about the rotation axis 350 a. Further, when the trailing endof the document G which is transported backward at the dischargetransport part 307 travels from the sheet discharge transport path 307 ato the second sheet transport path 303 c, the branching member 308 keepsthe first attitude and permits the document G to be transported to thesecond sheet transport path 303 c.

Namely, the branching member 308 is normally disposed to block the pathbetween the reverse sheet transport path 303 b and the sheet dischargetransport path 307 a and to provide a direct connection between thesheet discharge transport path 307 a and the second sheet transport path303 c. When the document G is transported from the reverse sheettransport path 303 b, the branching member 308 is lifted by the leadingend of the document G and allowed to guide the document G to the sheetdischarge transport path 307 a. After the document G passes thebranching member 308, the claw 308 b falls by its own weight. When thedocument G is transported backward from the sheet discharge transportpath 307 a, the branching member 308 guides the document G to the secondsheet transport path 303 c.

The size of a document G held on the document tray 301 is detected bydocument size sensors 309 a, 309 a (see FIGS. 1-3) provided in adocument holding part of the document tray 301. The presence and absenceof a document G on the document tray 301 is detected by a documentdetection sensor 309 b (see FIGS. 1-5) which is provided in the documenttray 301, in the vicinity of the pick-up roller 311 in the firsttransport guide member 310. The pair of upstream transport rollers 304,while stopped, abuts on and aligns the leading end of the document Gtransported from the retard roller 312. Later, the pair of upstreamtransport rollers 304 is rotationally driven in synchronization with thetiming of scanning. The thus transported document G is detected by atransport sensor 309 c (see FIGS. 1, 2, 4, and 5) which is positioneddownwardly of a junction between the first sheet transport path 303 aand the second sheet transport path 303 c in the transport direction Y1and upwardly of the pair of upstream transport rollers 304. The documentG discharged by the pair of discharge rollers 307 b is detected by adischarge sensor 309 d (see FIGS. 1, 2, 4, and 5) provided on adischarge side near the pair of discharge rollers 307 b. In thisexample, transport system rollers (such as the pair of upstreamtransport rollers 304, the pair of downstream transport rollers 305, andthe pair of discharge rollers 307 b) are driven by a transport systemdriving unit (not shown).

When the above-described image reading apparatus 200 receives a commandto scan an image on a document G in a moving original exposure mode, thelight source unit 420 stays at the fixed position V shown in FIG. 2, andthe automatic document feeder 300 feeds the document G in the transportdirection Y1 over the light source unit 420. Namely, one or moredocuments G held on the document tray 301 are pulled out by the pick-uproller 311, separated from each other by the retard roller 312 and theseparation roller 324, and transported one by one into the first sheettransport path 303 a. After the transport sensor 309 c confirms that thedocument G is transported in the first sheet transport path 303 a, thepair of upstream transport rollers 304 aligns the leading edge of thedocument G in order to prevent diagonal travelling. Later, at apredetermined timing of scanning, the pair of upstream transport rollers304 feeds the document G to the document reading glass 412, withreversing the document G from one side to the other.

While the document G passes over the document reading glass 412, oneside (the front side) of the document G is irradiated by the lightsource unit 420 through the document reading glass 412. The light isreflected by the one side (the front side) of the document G and then bythe first mirror 422, has its optical path changed 180° by the secondmirror 431 and the third mirror 432 in the mirror unit 430, travelsthrough the condensing lens 440, and forms an image on thelight-receiving surface 451 of the photoelectric transducer 450, wherethe document image is read and converted into electric image data.

For single-side (front-side) scanning, after one side (the front side)of the document G is scanned, the document G is pulled away from thedocument reading glass 412 by the pair of downstream transport rollers305, guided through the sheet discharge transport path 307 a, anddischarged to the discharge tray 302 by the pair of discharge rollers307 b rotating in the forward direction.

For double-side (front-and-back-side) scanning, the document G is notdischarged to the discharge tray 302 after one side (the front side) ofthe document G is scanned. Instead, the document G is transported to putits trailing end in the sheet discharge transport path 307 a, andtransported backward in the reverse transport direction Y2 by the pairof discharge rollers 307 b rotating in the reverse direction. Via thebranching member 308, the document G is guided into the second sheettransport path 303 c. Through the second sheet transport path 303 c, thedocument G returns to the first sheet transport path 303 a. Then, thedocument G is transported by the pair of upstream transport rollers 304and has the other side (the back side) scanned over the document readingglass 412. The reading operation by the photoelectric transducer 450 issimilar to the one for the single-side scanning, and is not describedherein.

After both sides are scanned, the document G is allowed to pass throughthe sheet discharge transport path 307 a and is discharged to thedischarge tray 302 by the pair of discharge rollers 307 b rotating inthe forward direction.

Other members illustrated in FIGS. 3, 4 and 5 with referencenumerals/symbols but not described above will be described later.

(Sheet Transport Guide Section)

FIGS. 6 and 7 are perspective views of the automatic document feeder 300in the image reading apparatus 200 shown in FIG. 4, with the firsttransport guide member 310 being closed and opened, respectively. FIG. 8is a partial perspective view of the automatic document feeder 300 shownin FIG. 4, showing the first transport guide member 310, the secondtransport guide member 320, the swingable member 330, and the biasingmember 340. In FIGS. 6 and 8, the automatic document feeder 300 isillustrated with the front cover and the frame FL removed. In FIG. 7,the automatic document feeder 300 is illustrated with the front cover,the frame FL, and the biasing member 340 removed.

FIGS. 9-11 are schematic front views of the sheet transport part in theautomatic document feeder 300 shown in FIG. 4. In FIG. 9, the firsttransport guide member 310 is in the process of opening or closing by anopening/closing operation by an operator OP, which causes the secondtransport guide member 320 to move rotationally between the firstposition and the second position. In FIG. 10, the first transport guidemember 310 is fully open, which causes the second transport guide member320 to be at the second position. In FIG. 11, the first transport guidemember 310 is fully open, and the second transport guide member 320 isbrought to a third position by an opening operation by an operator OP.

FIG. 12 is a perspective view of the second transport guide member 320,the swingable member 330, and the biasing member 340, extracted from theautomatic document feeder 300.

FIGS. 13(a)-13(f) represent a general configuration of the swingablemember 330 in the automatic document feeder 300, respectively being aback view, a plan view, a front view, a bottom view, a left side view,and a right side view of the swingable member 330.

FIGS. 14(a) and 14(b) are front perspective views of the swingablemember 330 in the automatic document feeder 300, as seen from top rightand top left, respectively.

As shown in FIGS. 6-14, the sheet transport guide section 306 is furtherequipped with a swingable member 330.

The swingable member 330 is swingable about a third axis P3 (see FIGS. 4and 9-11) extending in the width directions X, relative to the firsttransport guide member 310, at a different position from the first axisof the first transport guide member 310 (in this example, the firstswing axis 310 a).

To be more specific, the first transport guide member 310 is providedwith a fulcrum part 314 (see FIGS. 6, 7, and 8). The swingable member330 is provided swingably about the fulcrum part 314 in the firsttransport guide member 310. In this example, the fulcrum part 314 is afulcrum hole which is depressed in one of the width directions X. Theswingable member 330 includes a third swing axis 330 a extending in thewidth direction X. By means of the third swing axis 330 a, the swingablemember 330 can be inserted in and removed from the fulcrum part 314 inthe first transport guide member 310. The diameter of the fulcrum part314 is greater by a predetermined amount than that of the third swingaxis 330 a so as to permit a smooth swinging movement of the swingablemember 330. Owing to this arrangement, the swingable member 330 allowsthe third swing axis 330 a to be removably inserted in the fulcrum part314 in the first transport guide member 310. Hence, the swingable member330 can be arranged removably in the fulcrum part 314 in the firsttransport guide member 310, swingably about the third swing axis 330 a.

The swingable member 330 may be provided on at least one side (the frontside, the back side, or both) of the sides of the first transport guidemember 310 in the width directions X. In this example, the swingablemember 330 is provided only on one side (specifically, the front side)of the first transport guide member 310 in the width directions X.

In the automatic document feeder 300, the second transport guide member320 is arranged at a first position (the position shown in FIG. 4) whenthe first transport guide member 310 is closed, at a second position(the position shown in FIG. 10) where the second transport guide member320 is opened from the first position (specifically, opens by apredetermined angular degree) when the first transport guide member 310is opened (specifically, opened fully), or at a third position (theposition shown in FIG. 11) where the second transport guide member 320is opened from the second position.

The second position of the second transport guide member 320 may be, forexample, a position where the second transport guide member 320 opensfrom the first position by a predetermined angular degree, to such anextent that an operator OP (e.g. a user) can recognize that the secondtransport guide member 320 can be opened and closed, and/or, that anoperator OP can see a document G jammed at the second transport guidemember 320 on the far side of the first transport guide member 310 (inthis example, jammed in the second sheet transport path 303 c or thereverse sheet transport path 303 b). The third position of the secondtransport guide member 320 is set downstream of the second position inan open direction Q2 about the second axis P2.

First Embodiment

The automatic document feeder 300 according to First Embodiment isconfigured as below. When the first transport guide member 310 is openedor closed by an opening/closing operation by an operator OP (see FIG.9), the first transport guide member 310 moves in an opening/closingdirection about the first axis (in this example, the first swing axis310 a), followed by a swinging movement of the swingable member 330about the third axis P3 (in this example, the third swing axis 330 a).In synchronization with the swinging movement of the swingable member330, the second transport guide member 320 is caused to swing about thesecond axis P2 (in this example, the second swing axis 320 a).

To be more specific about this automatic document feeder 300, when thefirst transport guide member 310 is opened by an opening operation by anoperator OP for opening the first transport guide member 310, the firsttransport guide member 310 opens in an open direction Q1 (see FIG. 10,counterclockwise in front view) about the first swing axis 310 a,followed by a swinging movement of the swingable member 330 relative tothe first transport guide member 310. In synchronization with theswinging movement of the swingable member 330, the second transportguide member 320 is caused to swing in an open direction Q2 (see FIG.10, counterclockwise in front view) about the second swing axis 320 a.

Further in the automatic document feeder 300, when the first transportguide member 310 is closed by a closing operation by an operator OP forclosing the first transport guide member 310, the first transport guidemember 310 closes in a closing direction Q3 (see FIG. 10, clockwise infront view) about the first swing axis 310 a, followed by a swingingmovement of the swingable member 330 relative to the first transportguide member 310. In synchronization with the swinging movement of theswingable member 330, the second transport guide member 320 is caused toswing in a closing direction Q4 (see FIG. 10, clockwise in front view)about the second swing axis 320 a.

First Embodiment-1

In the automatic document feeder 300 according to First Embodiment-1,even when the second transport guide member 320 is opened or closed byan opening/closing operation by an operator OP, the first transportguide member 310 and the swingable member 330 are arranged not to swingin synchronization with an opening/closing movement of the secondtransport guide member 320 about the second swing axis 320 a.

To be more specific about this automatic document feeder 300, when thesecond transport guide member 320 is opened or closed by anopening/closing operation by an operator OP (see FIG. 11) while thefirst transport guide member 310 is open, the second transport guidemember 320 is arranged to be opened or closed about the second axis P2(in this example, the second swing axis 320 a), independently of thefirst transport guide member 310 and the swingable member 330.

Specifically, in the closed state, the second transport guide member 320is in proximity to or in contact with (in this example, in proximity to)the swingable member 330 in a swingable manner about the second swingaxis 320 a. The second transport guide member 320 may be brought intoproximity to or into contact with the swingable member 330 either by abiasing force applied by a biasing member toward the swingable member330 or by its own weight. In this example, the second transport guidemember 320 in the closed state is in proximity with the swingable member330, with an upstream end 320 e (see FIGS. 4, 5, and 9-12) in thetransport direction Y1 resting on a downstream end 301 a of the documenttray 301 in the transport direction Y1 (see FIGS. 4, 5, and 9-11) by itsown weight.

First Embodiment-2

In First Embodiment-2, the swingable member 330 has a reciprocating part332 and an abutting part 333. When the swingable member 330 swings aboutthe third axis P3 (in this example, the third swing axis 330 a) alongwith the opening movement of the first transport guide member 310, thereciprocating part 332 moves along a path extending in reciprocatingdirections (in this example, the crosswise directions Y) which areorthogonal or substantially orthogonal to the width directions X. Theabutting part 333 is provided on the reciprocating part 332 and arrangedto abut on the second transport guide member 320.

To be more specific about this automatic document feeder 300, theopening movement of the first transport guide member 310 is followed bya swinging movement of the swingable member 330 about the third swingaxis 330 a relative to the first transport guide member 310. At the sametime, the reciprocating part 332 of the swingable member 330 is causedto move in one of the reciprocating directions (the crosswise directionsY). Namely, the automatic document feeder 300 causes the reciprocatingpart 332 to reciprocate in the crosswise directions Y between the firstposition of the first transport guide member 310 where the firsttransport guide member 310 is closed (the position shown in FIG. 4) andthe second position of the first transport guide member 310 where thefirst transport guide member 310 is opened fully (the position shown inFIG. 10).

Specifically, the swingable member 330 has an elongated (stick-like)swingable member main body 331. The third swing axis 330 a is providedat an end of the swingable member main body 331, and the reciprocatingpart 332 is provided at the other end of the swingable member main body331.

The automatic document feeder main body 300 a includes a guide part FLa(see FIGS. 2-4 and 9-11) for guiding the reciprocating part 332 in thereciprocating directions (in this example, the crosswise directions Y).

The guide part FLa may be, for example, a rib member, an elongated bore,or a groove to be engaged with the reciprocating part 332 of theswingable member 330. In the present specification, the term “rib” meansa ridge elongated in a certain direction, the term “bore” means athrough bore, and the term “hole” means a blind hole.

In this example, the guide part FLa has an elongated bore FLa1 (seeFIGS. 3 and 11) extending in the crosswise directions Y. The guide partFLa may be also equipped with a limitation part for limiting anexcessive swinging movement of the first transport guide member 310 inthe open direction Q1 beyond the predetermined full-open position (theposition shown in FIG. 10) when the first transport guide member 310 isopened.

To be more specific, the automatic document feeder 300 is furtherequipped with a frame FL (in this example, a front frame) (see FIGS.9-11) provided in the automatic document feeder main body 300 a. Theframe FL is a plate-like member extending in both the height directionsZ and the crosswise directions Y in the automatic document feeder mainbody 300 a. The guide part FLa is provided in the frame FL.

Specifically, the frame FL is designed to receive the reciprocating part332 of the swingable member 330 in the elongated bore FLa1 of the guidepart FLa. An end of the elongated bore FLa1 in the crosswise directionsY serves as a limitation part for limiting an excessive swingingmovement of the first transport guide member 310 in the open directionQ1 beyond the predetermined full-open position.

The reciprocating part 332 of the swingable member 330 is provided withan engagement portion 332 a (see FIGS. 6-8 and 12-14) to be engaged withthe guide part FLa of the frame FL. In this example, the engagementportion 332 a has a circular shape in front view (as seen in the widthdirections X).

The width of the elongated bore FLa1 is greater by a predeterminedamount than the diameter of the engagement portion 332 a so as to permita smooth reciprocating movement of the reciprocating part 332. Owing tothis arrangement, the frame FL allows a smooth sliding movement of theengagement portion 332 a of the reciprocating part 332 along theelongated bore FLa1. Thus, the swingable member 330 allows thereciprocating part 332 of the swingable member 330 to reciprocatesmoothly in the crosswise directions Y along the elongated bore FLa1 inthe frame FL.

In the state where the first transport guide member 310 is closed, theswingable member 330 is oriented such that an imaginary straight line α(see FIG. 12) which passes through the center of the third swing axis330 a and the center of the reciprocating part 332 is level in thecrosswise directions Y.

The abutting part 333 has a sliding surface 333 a (see FIGS. 4 and 6-14)which slides along the second transport guide member 320. The slidingsurface 333 a of the abutting part 333 has a curved convex shape whichcurves in the crosswise directions Y (FIGS. 8 and 12-14). In the statewhere the first transport guide member 310 is closed, the abutting part333 is oriented in the height directions Z. An end face of the abuttingpart 333 facing the second transport guide member 320 in the heightdirections Z constitutes the sliding surface 333 a.

The second transport guide member 320 is equipped with a sliding contactguide part 322 (see FIGS. 6-12). When the reciprocating part 332 of theswingable member 330 moves in one of the reciprocating directions (inthis example, to the left in front view in the crosswise directions Y),the sliding contact guide part 322 is arranged to come into slidingcontact with the abutting part 333 of the swingable member 330, andthereby to cause the second transport guide member 320 to be liftedabout the second axis P2 (in this example, the second swing axis 320 a).

The sliding contact guide part 322 may be, for example, a rib member, anelongated bore, or a groove to be engaged with the abutting part 333 ofthe swingable member 330.

In this example, the second transport guide member 320 has aplate-shaped second transport guide member main body 321. The secondtransport guide member main body 321 has, in thickness directionsthereof, a second sheet guide surface 320 b on one side and a thirdsheet guide surface 320 c on the other side. The separation roller 324is provided on the one side of the second transport guide member mainbody 321. The sliding contact guide part 322 is provided on a side 320 f(in this example, the front side) (see FIGS. 4-12), which is a sidecloser to the swingable member 330 in the width directions X of thesecond transport guide member main body 321. The sliding contact guidepart 322 is a rib member which protrudes outwardly in one of the widthdirections X (in this example, to the front side). The sliding contactguide part 322 has a sliding contact surface 322 a (see FIGS. 4-12)which comes into sliding contact with the sliding surface 333 a of theabutting part 333 in the swingable member 330.

During a sliding movement of the swingable member 330, a point ofcontact between the sliding contact surface 322 a and the swingablemember 330 (in this example, the sliding surface 333 a) leaves a locusof movement β (see FIGS. 4, 9, and 10). In the state where the firsttransport guide member 310 is closed, the sliding contact surface 322 aintersects the locus of movement β between the first position of thefirst transport guide member 310 (see FIG. 4) and the second position ofthe first transport guide member 310 (see FIG. 10). In this example, inthe state where the first transport guide member 310 is closed, thesliding contact surface 322 a is an inclined surface in which one sideof the sliding contact surface 322 a in the crosswise directions Y (inthis example, the left side in front view) which is a side closer to thethird swing axis 330 a is lower than the other side (in this example,the right side in front view) which is a far side of the third swingaxis 330 a

The sliding contact guide part 322 is arranged to lift the secondtransport guide member 320 in the open direction Q2 about the secondswing axis 320 a by such a predetermined degree that, when the firsttransport guide member 310 is open (fully open), an operator OP canrecognize that the second transport guide member 320 can be opened andclosed (see FIG. 10).

Specifically, the second transport guide member main body 321 and thesliding contact guide part 322 are formed as a single piece toconstitute the second transport guide member 320.

First Embodiment-3

In First Embodiment-3, the swingable member 330 further includes asupporting part 334 (see FIGS. 6-14). The abutting part 333 is supportedby the reciprocating part 332 by means of the supporting part 334.

To be more specific, in the state where the first transport guide member310 is closed, the supporting part 334 is oriented in the crosswisedirections Y. An end of the supporting part 334 is arranged at an end ofthe swingable member main body 331 on which the reciprocating part 332is mounted, and another end is arranged at an end of the abutting part333 opposite to the sliding surface 333 a. In this example, thesupporting part 334 is provided at a far side of the sliding contactguide part 322 relative to the center of (specifically, provided lowerthan the center of) the swingable member main body 331 in the heightdirections Z. The supporting part 334 is flexible.

Specifically, the swingable member main body 331, the third swing axis330 a, the reciprocating part 332, the abutting part 333, and thesupporting part 334 are formed as a single piece to constitute theswingable member 330.

Materials for the swingable member 330 include, for example, resins(such as polyacetal resins and polyamide resins) which have excellentelasticity (particularly, elasticity at the supporting part 334) andexcellent slipping property (particularly, slipping property at theabutting part 333).

First Embodiment-4

In First Embodiment-4, the automatic document feeder 300 also includes abiasing member 340 (see FIGS. 1-4, 6, and 8-12) provided between thereciprocating part 332 of the swingable member 330 and the frame FL. Thebiasing member 340 biases, by means of the swingable member 330, thefirst transport guide member 310 in the open direction Q1 about thefirst axis (in this example, the first swing axis 310 a).

To be more specific, the biasing member 340 is a long, general-purposecoil spring. In the state where the first transport guide member 310 isclosed, the biasing member 340 is oriented in the reciprocatingdirections (in this example, the crosswise directions Y) and arrangedbetween the reciprocating part 332 and the frame FL.

Specifically, the frame FL is provided with a latch portion FLb (in thisexample, a latch bore) (see FIGS. 3, 4, and 9-11). The reciprocatingpart 332 is provided with a latch portion 332 b (in this example, alatch bore) (see FIGS. 3, 6-8, and 12-14). An end of the biasing member340 is connected with the latch portion FLb of the frame FL, and anotherend is connected with the latch portion 332 b of the reciprocating part332.

In this example, the automatic document feeder 300 further includes lockmechanisms 360 (see FIGS. 3 and 7) for releasably locking the firsttransport guide member 310 on the automatic document feeder main body300 a when the first transport guide member 310 is closed.

Each lock mechanism 360 may be, for example, a fit engagement lockmechanism for locking the first transport guide member 310 on theautomatic document feeder main body 300 a by releasable fit engagement,or a lever lock mechanism for releasably latching and locking the firsttransport guide member 310 on the automatic document feeder main body300 a by means of a lever having a gripper to be held by a user.

The lock mechanisms 360 in this example are fit engagement lockmechanisms. Each lock mechanism 360 includes a recess 361 which isdepressed in one of the width direction X and a protrusion 362 whichprotrudes in the width direction X to be latched in the recess 361.Either of the recess 361 or the protrusion 362 (in this example, therecess 361) is provided with respect to the first transport guide member310, and the other one (in this example, the protrusion 362) is providedwith respect to the automatic document feeder main body 300 a. Further,either of the recess 361 or the protrusion 362 (in this example, theprotrusion 362) is biased by a biasing member such as a spring (notshown) toward the center in the width directions X (in this example,biased in the protruding direction), but is permitted to move outwardlyin the width directions X (in this example, to move in the retractingdirection) against the biasing force of the biasing member.

First Embodiment-5

In First Embodiment-5, when the first transport guide member 310 isopened (specifically, opened fully), the first transport guide member310 is arranged to stop at its first position (see FIGS. 10 and 11)where the center of gravity M1 of the first transport guide member 310(see FIGS. 10 and 11) is on a closed side of the first transport guidemember 310 (a side to which the first transport guide member 310 closesby its own weight) (on the right side in FIGS. 10 and 11) relative to animaginary vertical line γ1 (see FIGS. 10 and 11) which passes throughthe first axis P1. In this description, the imaginary vertical line γ1is a straight line perpendicular to a horizontal plane.

In this example, the first transport guide member 310 is arranged tostop at its first position by the biasing member 340 which limitsrotational movement of the first transport guide member 310 in theclosing direction Q3.

First Embodiment-6

In First Embodiment-6, the second transport guide member 320 is arrangedto be brought to its second position (the position shown in FIG. 10) bythe swingable member 330 which swings with the opening/closing movementof the first transport guide member 310.

First Embodiment-7

In First Embodiment-7, the second transport guide member 320 is arrangedto be rotatably opened and closed at its second position (the positionshown in FIG. 10). Namely, if a user opens or closes the secondtransport guide member 320 from the second position and lets go of thesecond transport guide member 320 at a downstream side in the opendirection Q2 about the second axis P2, the second transport guide member320 is arranged to rotate (fall) by its own weight.

First Embodiment-8

In First Embodiment-8, the second transport guide member 320 is arrangedto stop at its third position (the position shown in FIG. 11). Namely,if the second transport guide member 320 is opened from the secondposition, the second transport guide member 320 is arranged to stop at adownstream side in the open direction Q2 about the second axis P2.

To be more specific, when the second transport guide member 320 isopened, the second transport guide member 320 is arranged to stop at thethird position (the position shown in FIG. 11) where the center ofgravity M2 of the second transport guide member 320 (see FIG. 11) is ona closed side of the second transport guide member 320 (a side to whichthe second transport guide member 320 closes by its own weight) (on theright side in FIG. 11) relative to an imaginary vertical line γ2 (seeFIG. 11) which passes through the second axis P2. In this description,the imaginary vertical line γ2 is a straight line perpendicular to ahorizontal plane.

In this example, the second transport guide member 320 is arranged to belatched (locked) (to be stopped) at its third position by fit engagementwith the automatic document feeder main body 300 a (specifically, anouter cover member 300 x).

FIGS. 15 and 16 are schematic sectional views showing examples of anengagement arrangement by which the second transport guide member 320 isengaged with the automatic document feeder main body 300 a by fitengagement when the second transport guide member 320 stops at its thirdposition. In FIG. 15, an exemplary dent 320 g in the second transportguide member 320 is engaged with an exemplary stud 381 a in theautomatic document feeder main body 300 a. In FIG. 16, an exemplary stud391 a in the second transport guide member 320 is engaged with anexemplary dent 300 b in the automatic document feeder main body 300 a.

The second transport guide member 320 is provided with a dent 320 g (seeFIG. 15), or a stud 391 a (see FIG. 16) which retractably projects undera predetermined pressure.

——Fit Engagement Arrangement in FIG. 15——

In the arrangement shown in FIG. 15, the second transport guide member320 is provided with a dent 320 g. The dent 320 g is a curved recess inthis example, but may be a V-shaped recess with inclined surfacesinstead.

The outer cover member 300 x is provided with a stud-like member 380.The stud-like member 380 is composed of an advanceable/retractablemember 381 having a stud 381 a, a housing 382 which houses theadvanceable/retractable member 381 reciprocably in advancing/retractingdirections S, and a biasing member 383 (in this example, ageneral-purpose coil spring) which biases the advanceable/retractablemember 381 in such a direction that the stud 381 a projects from theouter cover member 300 x.

A tip end of the stud 381 a (a portion to be in contact with the dent320 g in the second transport guide member 320) is shaped like a curvedbump, but may be shaped like a triangular bump instead.

The biasing member 383 is arranged between a back surface 381 b of theadvanceable/retractable member 381 opposite to the stud 381 a and abottom surface 382 a of the housing 382 facing the back surface 381 b ofthe advanceable/retractable member 381 opposite to the stud 381 a.Specifically, an end of the biasing member 383 is anchored at a latchportion 381 c (in this example, a latch hole) in the back surface 381 bof the advanceable/retractable member 381, and the other end of thebiasing member 383 is anchored at a latch portion 382 b (in thisexample, a latch hole) in the bottom surface 382 a of the housing 382.

——Fit Engagement Arrangement in FIG. 16——

In the arrangement shown in FIG. 16, the second transport guide member320 is provided with a stud-like member 390 including a stud 391 a. Thestud-like member 390 is composed of an advanceable/retractable member391 having the stud 391 a, a housing 392 which houses theadvanceable/retractable member 391 reciprocably in advancing/retractingdirections S, and a biasing member 393 (in this example, ageneral-purpose coil spring) which biases the advanceable/retractablemember 391 in such a direction that the stud 391 a projects from thesecond transport guide member 320.

A tip end of the stud 391 a (a portion to be in contact with the dent300 b in the outer cover member 300 x) is shaped like a triangular bump,but may be shaped like a curved bump instead.

The biasing member 393 is fitted in between a back surface 391 b of theadvanceable/retractable member 391 opposite to the stud 391 a and abottom surface 392 a of the housing 392 facing the back surface 391 b ofthe advanceable/retractable member 391 opposite to the stud 391 a.Specifically, an end of the biasing member 393 is anchored at a latchportion 391 c (in this example, a latch hole) in the back surface 391 bof the advanceable/retractable member 391, and the other end of thebiasing member 393 is anchored at a latch portion 392 b (in thisexample, a latch hole) in the bottom surface 392 a of the housing 392.

The dent 300 b in the outer cover member 300 x in this example is aV-shaped recess with inclined surfaces, but may be a curved recessinstead.

Alternatively, in the arrangement shown in FIG. 15, the outer covermember 300 x may be provided with a dent, and the second transport guidemember 320 may be provided with a stud-like member. In the arrangementshown in FIG. 16, the second transport guide member 320 may be providedwith a dent, and the outer cover member 300 x may be provided with astud-like member.

The first transport guide member 310 (for example, the one in FirstEmbodiment-5) may be further arranged just as the second transport guidemember 320 exemplified in FIGS. 15 and 16. Namely, with the biasingmember 340 removed, the first transport guide member 310 may be arrangedto be latched (locked) (to be stopped) at its second position by fitengagement with the automatic document feeder main body 300 a(specifically, the outer cover member 300 x).

Additionally, when the second transport guide member 320 is opened, thesecond transport guide member 320 may be arranged to stop at its thirdposition where the center of gravity M2 of the second transport guidemember 320 is on an open side of the second transport guide member 320(a side to which the second transport guide member 320 opens by its ownweight) (on the left side in FIG. 11) relative to the imaginary verticalline γ2. Alternatively, when the second transport guide member 320 isopened, the second transport guide member 320 may be arranged to belimited by the first transport guide member 310 and to stop at the thirdposition where the center of gravity M2 of the second transport guidemember 320 is on an open side of the second transport guide member 320relative to the imaginary vertical line γ2. For example, the secondtransport guide member 320 which makes a rotational movement in the opendirection Q2 by its own weight may be prevented from making therotational movement in the open direction Q2 when the second transportguide member 320 comes into fit engagement with the automatic documentfeeder main body 300 a (specifically, the outer cover member 300 x) orwhen the second transport guide member 320 reaches its third positionand comes into contact with the first transport guide member 310stopping at its second position.

First Embodiment-9

Regarding the second transport guide member 320, the degree of openingat its second position (the position shown in FIG. 10) and the degree ofopening at its third position (the position shown in FIG. 11) aredifferent by d1 (angular degree) (see FIG. 11). Similarly, the degree ofopening at its second position and the degree of opening at its firstposition (the position shown in FIG. 4) are different by d2 (angulardegree) (see FIG. 10). In First Embodiment-9, the difference d1 isgreater than the difference d2.

First Embodiment-10

In First Embodiment-10, an opening d3 (clearance) (see FIG. 11) betweenthe second transport guide member 320 at its third position (theposition shown in FIG. 11) and the third transport guide member 350 iswider than an opening d4 (clearance) (see FIG. 11) between the secondtransport guide member 320 at its third position and the first transportguide member 310 in an open state.

Second Embodiment

FIG. 17 is an enlarged schematic front view of another example of thesheet transport part in the automatic document feeder 300 of the imagereading apparatus 200 shown in FIG. 4, with the first transport guidemember 310 closed and the second transport guide member 320 at the firstposition. FIGS. 18-20 are schematic front views of the sheet transportpart in the automatic document feeder 300 shown in FIG. 17. In FIG. 18,the first transport guide member 310 is in the process of opening orclosing by an opening/closing operation by an operator OP, which causesthe second transport guide member 320 to move rotationally between thefirst position and the second position. In FIG. 19, the first transportguide member 310 is fully open, which causes the second transport guidemember 320 to be at the second position. In FIG. 20, the first transportguide member 310 is fully open, and the second transport guide member320 is brought to the third position by an opening operation by anoperator OP.

The automatic document feeder 300 shown in FIG. 17 is different from theautomatic document feeder 300 shown in FIG. 4 in that the biasing member340 and the latch portion FLb in the frame FL are removed, and that theelongated bore FLa1 in the guide part FLa of the frame FL is extended.

In the automatic document feeder 300 shown in FIG. 17, the descriptionfor the components and portions substantially identical to thosementioned in the automatic document feeder 300 shown in FIG. 4 isomitted by using the same reference numerals and symbols.

Second Embodiment-1

In Second Embodiment-1, when the first transport guide member 310 isopened (specifically, opened fully), the first transport guide member310 is arranged to stop at its second position (see FIGS. 19 and 20). Atthe second position, the center of gravity M1 of the first transportguide member 310 (see FIGS. 19 and 20) is on an open side of the firsttransport guide member 310 (a side to which the first transport guidemember 310 opens by its own weight) (on the left side in FIGS. 19 and20) relative to an imaginary vertical line γ1 (see FIGS. 19 and 20)which passes through the first axis P1.

In this example, when the first transport guide member 310 movesrotationally in the open direction Q1 by its own weight and reaches itssecond position, the reciprocating part 332 of the swingable member 330is latched in the guide part FLa of the frame FL. This action limits therotational movement of the first transport guide member 310 in the opendirection Q1, and causes the first transport guide member 310 to stop atthe second position. For example, the first transport guide member 310may be arranged just as the second transport guide member 320exemplified in FIGS. 15 and 16. Namely, the first transport guide member310 may be arranged to be latched (locked) (to be stopped) at its secondposition by fit engagement with the automatic document feeder main body300 a (specifically, the outer cover member 300 x).

Second Embodiment-2

In Second Embodiment-2, the second transport guide member 320 isarranged to be brought to its second position (the position shown inFIG. 19) by the swingable member 330 which swings with theopening/closing movement of the first transport guide member 310.

Second Embodiment-3

In Second Embodiment-3, the second transport guide member 320 isarranged to be rotatably opened and closed at its second position (theposition shown in FIG. 19). Namely, if a user opens and closes thesecond transport guide member 320 from the second position and lets goof the second transport guide member 320 at a downstream side in theopen direction Q2 about the second axis P2, the second transport guidemember 320 is arranged to rotate (fall) by its own weight.

Second Embodiment-4

In Second Embodiment-4, the second transport guide member 320 isarranged to stop at its third position (the position shown in FIG. 20).Namely, if the second transport guide member 320 is opened from thesecond position, the second transport guide member 320 is arranged tostop at a downstream side in the open direction Q2 about the second axisP2.

To be more specific, when the second transport guide member 320 isopened, the second transport guide member 320 is arranged to stop at itsthird position (the position shown in FIG. 20) where the center ofgravity M2 of the second transport guide member 320 (see FIG. 20) is onan open side of the second transport guide member 320 (a side to whichthe second transport guide member 320 opens by its own weight) (on theleft side in FIG. 20) relative to an imaginary vertical line γ2 (seeFIG. 20) which passes through the second axis P2. Alternatively, whenthe second transport guide member 320 is opened, the second transportguide member 320 is arranged to be limited by the first transport guidemember 310 and to stop at its third position where the center of gravityM2 of the second transport guide member 320 is on an open side of thesecond transport guide member 320 relative to the imaginary verticalline γ2. For example, the second transport guide member 320 which makesa rotational movement in the open direction Q2 by its own weight isarranged to be prevented from making the rotational movement in the opendirection Q2 when the second transport guide member 320 comes into fitengagement (see FIGS. 15 and 16) with the automatic document feeder mainbody 300 a (specifically, outer cover member 300 x) or when the secondtransport guide member 320 reaches its third position and comes intocontact with the first transport guide member 310 (in this example, thefirst registration roller 304 a) stopping at its second position.

Additionally, when the second transport guide member 320 is opened, thesecond transport guide member 320 may be arranged to stop at its thirdposition where the center of gravity M2 of the second transport guidemember 320 is on a closed side of the second transport guide member 320(a side to which the second transport guide member 320 closes by its ownweight) (on the right side in FIG. 20) relative to the imaginaryvertical line γ2 which passes through the second axis P2. For example,the second transport guide member 320 may be arranged to be latched(locked) (to be stopped) at its third position by fit engagement withthe automatic document feeder main body 300 a (specifically, an outercover member 300 x).

Second Embodiment-5

Regarding the second transport guide member 320, the degree of openingat its second position (the position shown in FIG. 19) and the degree ofopening at its third position (the position shown in FIG. 20) aredifferent by d1 (angular degree) (see FIG. 20). Similarly, the degree ofopening at its second position and the degree of opening at its firstposition (the position shown in FIG. 17) are different by d2 (angulardegree) (see FIG. 19). In Second Embodiment-5, the difference d1 isgreater than the difference d2.

Second Embodiment-6

In Second Embodiment-6, an opening d3 (clearance) (see FIG. 20) betweenthe second transport guide member 320 at its third position (theposition shown in FIG. 20) and the third transport guide member 350 iswider than an opening d4 (clearance) (see FIG. 20) between the secondtransport guide member 320 at its third position and the first transportguide member 310 in an open state.

Third Embodiment

In Third Embodiment, the automatic document feeder 300 in any of Firstand Second

Embodiments is provided with a recess 325 as shown in FIG. 12 (see alsoFIGS. 11, 20, and 22) at an end of the second transport guide member 320(the upstream end 320 e in the transport direction Y1) opposite to theswing fulcrum of the second transport guide member 320 (the second axisP2). The recess 325 in the second transport guide member 320 is providedon an operation side X1 (see FIG. 11) relative to the center in thewidth directions X. In this context, the operation side refers to a sidewhere an operator OP operates the image reading apparatus 200 (the imageforming apparatus 100).

To be more specific, the recess 325 is defined by an insertion part 325a having an upper opening 325 x, and a grip 325 b. The insertion part325 a is depressed downwardly in the second sheet guide surface 320 b ofthe second transport guide member 320. The insertion part 325 a is opento an upstream side in the transport direction Y1 and enables anoperator OP to insert his/her fingers. In this insertion part 325 a, thegrip 325 b covers a downstream side of the upper opening 325 x in thetransport direction Y1 and enables an operator OP to hold the grip 325b. In order to inform an operator OP of the presence of the grip 325 b,an index 325 c, such as a sticker in a predetermined color (green inthis example), is attached on a top surface of the grip 325 b.

Fourth Embodiment

In Fourth embodiment, the automatic document feeder 300 in any of Firstto Third Embodiments is further equipped with an interlock detectionswitch 370 (see FIGS. 4, 5, and 9-11) for prohibiting the action of theapparatus (the action of the automatic document feeder 300), and anactivating part 323 (see FIGS. 4, 5, 7, and 9-12) for activating theinterlock detection switch 370.

FIGS. 21 and 22 illustrate operations of the interlock detection switch370 and the activating part 320. FIG. 21 is a side perspective view ofthe interlock detection switch 370 and the activating part 323, with thefirst transport guide member 310 fully open and the second transportguide member 320 in the process of opening or closing. FIG. 22 is aschematic front view which represents a positional relationship betweenthe interlock detection switch 370 and the activating part 323, with thefirst transport guide member 310 and the second transport guide member320 fully open. Incidentally, the arrangement according to FourthEmbodiment is applicable to both of the automatic document feeders 300shown in FIG. 4 and in FIG. 17. Hence, FIG. 22 depicts an arrangementfor the automatic document feeder 300 shown in FIG. 4 as a typicalexample, and illustration of an arrangement for the automatic documentfeeder 300 shown in FIG. 17 is omitted.

The interlock detection switch 370 is provided in either of the firsttransport guide member 310 or the second transport guide member 320 (inthis example, the first transport guide member 310), and the activatingpart 323 is provided in the other transport guide member (in thisexample, the second transport guide member 320).

The interlock detection switch 370 and the activating part 323 arepositioned such that, in the state where the first transport guidemember 310 is closed (namely, in the state where the first transportguide member 310 and the second transport guide member 320 are bothclosed), the interlock detection switch 370 is turned on by theactivating part 323 (namely, positioned to cancel the prohibition of theaction of the apparatus, in other words, positioned to permit the actionof the apparatus) (see FIGS. 4 and 5). In this example, the interlockdetection switch 370 and the activating part 323 are disposed on the farside (specifically, the rear side) (see FIG. 21) in the width directionsX of the automatic document feeder 300.

The first axis in the first transport guide member 310 (in this example,the first swing axis 310 a) and the second axis P2 in the secondtransport guide member 320 (in this example, the second swing axis 320a) are provided at different positions from each other (see FIGS. 2, 4,5, 8-11, and 22).

The interlock detection switch 370 is a switch (specifically, amicroswitch) equipped with an actuator part 371 (see FIGS. 4, 5, 9-11,21, and 22) which swings about an axis extending in the width directionsX, and a switch part 372 (see FIGS. 4, 5, 9-11, 21, and 22) which keepsa deactivated state (a switch-off state) when no external force isapplied to the actuator part 371, and which turns into an activatedstate (a switch-on state) by a swinging movement of the actuator part371 when an external force is applied to the actuator part 371.

Specifically, the second transport guide member main body 321 and theactivating part 323 are formed as a single piece to constitute thesecond transport guide member 320.

Fifth Embodiment

In Fifth Embodiment, the automatic document feeder 300 according to anyof First to Fourth Embodiments is provided with through-windows 308 c(FIGS. 4, 5, and 9-11) in the branching member 308, each of whichpenetrates from the second sheet transport path 303 c side to thereverse sheet transport path 303 b side.

FIG. 23 is a top, side perspective view of a part around the branchingmember 308, for explaining the through-windows 308 c provided in thebranching member 308, with the first transport guide member 310 fullyopen and the second transport guide member 320 removed. Incidentally,the arrangement according to Fifth Embodiment is applicable to both ofthe automatic document feeders 300 shown in FIG. 4 and in FIG. 17.Hence, FIG. 23 depicts an arrangement for the automatic document feeder300 shown in FIG. 4 as a typical example, and illustration of anarrangement for the automatic document feeder 300 shown in FIG. 17 isomitted.

As shown in FIG. 23, a plurality of through-windows 308 c-308 c arearranged side by side in the width directions X.

(Paper Jam Clearing Operation by an Operator)

In the automatic document feeder 300, if a document G is jammed at thesecond transport guide member 320 on the far side of the first transportguide member 310 (in this example, in the second sheet transport path303 c or the reverse sheet transport path 303 b), a paper jam clearingoperation for removing the document G jammed at the second transportguide member 320 on the far side of the first transport guide member 310(in this example, in the second sheet transport path 303 c or thereverse sheet transport path 303 b) is carried out in the followingmanner. For a start, an operator OP opens the first transport guidemember 310 toward the first position (see FIG. 10) or the secondposition (see FIG. 19).

Specifically, when the lock mechanism 360 is unlocked by an operation byan operator OP for opening the first transport guide member 310 (seeFIG. 9), the automatic document feeder 300 shown in FIG. 4 allows thefirst transport guide member 310 to be automatically opened (openedfully) in the open direction Q1 by a biasing force of the biasing member340 in the open direction Q1, and to stop at the first position of thefirst transport guide member 310 (see FIG. 10). To be more specific, thefirst transport guide member 310 is retained so as not to make arotational movement in the closing direction Q3 from the first position.In the automatic document feeder 300 shown in FIG. 17, when an operatorOP opens (fully opens) the first transport guide member 310 in the opendirection Q1, the first transport guide member 310 stops at its secondposition (in this example, the reciprocating part 332 is latched on theguide part FLa) (see FIG. 19). To be more specific, the first transportguide member 310 is limited so as not to make a rotational movement inthe open direction Q1 from the second position.

At this time, the opening movement of the first transport guide member310 in the open direction Q1 about the first swing axis 310 a isfollowed by a swinging movement of the swingable member 330 about thethird swing axis 330 a, which in turn causes a swinging movement of thesecond transport guide member 320 in the open direction Q2 about thesecond swing axis 320 a toward its second position.

To be more specific, the swingable member 330 swings about the thirdswing axis 330 a relative to the first transport guide member 310, andthe reciprocating part 332 moves in the crosswise directions Y(specifically, along the guide part FLa of the frame FL) toward one sidein the crosswise directions Y (in this example, to the left in frontview). Then, the sliding surface 333 a of the abutting part 333 providedat the reciprocating part 332 (specifically, the abutting part 333provided at the reciprocating part 332 by means of the supporting part334) is caused to slide along the sliding contact guide part 322 of thesecond transport guide member 320. At this time, the abutting part 333of the reciprocating part 332 which is moving to the one side in thecrosswise directions Y lifts the second transport guide member 320 tothe second position, by sliding along the sliding contact surface 322 awhich intersects with the locus of movement β (see FIGS. 9 and 18).Specifically, the second transport guide member 320 is lifted toward itssecond position in the open direction Q2 about the second swing axis 320a (see FIGS. 10 and 19) to such an extent that an operator OP canrecognize that the second transport guide member 320 can be opened andclosed. As a result, an operator OP can recognize that the secondtransport guide member 320 can be opened and closed. Additionally oralternatively, an operator OP can visually recognize that a document Gis jammed at the second transport guide member 320 on the far side ofthe first transport guide member 310 (in this example, in the secondsheet transport path 303 c or the reverse sheet transport path 303 b).

Then, an operator OP opens the second transport guide member 320. In theautomatic document feeder 300 shown in FIG. 4, the second transportguide member 320 is opened by an operator OP in the open direction Q2and brought to its third position (for example, the second transportguide member 320 is caused to stop by fit engagement) (see FIG. 11). Inthe automatic document feeder 300 shown in FIG. 17, the second transportguide member 320 is opened by an operator OP in the open direction Q2and brought to its third position (for example, the second transportguide member 320 abuts on the first transport guide member 310, and thefirst transport guide member 310 limits the rotational movement of thesecond transport guide member 320 in the open direction Q2 and causesthe second transport guide member 320 to stop). In this manner, anoperator OP can easily remove a document G jammed in the second sheettransport path 303 c (see FIG. 5) or a document G jammed in the reversesheet transport path 303 b (specifically, a document G visible throughthe through-windows 308 c in the branching member 308).

After this paper jam clearing operation, an operator OP closes thesecond transport guide member 320 toward the second position (see FIGS.10 and 19) by an operation for closing the second transport guide member320. Specifically, in response to an operation by an operator OP forclosing the second transport guide member 320, the second transportguide member 320 moves in the closing direction Q4 to the secondposition, where the sliding contact guide part 322 of the secondtransport guide member 320 rests on the abutting part 333 of theswingable member 330 by its own weight (see FIGS. 10 and 19).

Next, an operator OP closes the first transport guide member 310 by anoperation for closing the first transport guide member 310 (see FIGS. 4and 17).

Specifically, in the automatic document feeder 300 shown in FIG. 4, thefirst transport guide member 310 is closed in the closing direction Q3by an operation by an operator OP for closing the first transport guidemember 310, against the biasing force of the biasing member 340 in theopen direction Q1 (see FIG. 9), and the first transport guide member 310is locked by the lock mechanism 360 (see FIG. 4). In the automaticdocument feeder 300 shown in FIG. 17, the first transport guide member310 is closed in the closing direction Q3 by an operation by an operatorOP for closing the first transport guide member 310 (see FIG. 18), andis locked by the lock mechanism 360 (see FIG. 17).

At this time, the closing movement of the first transport guide member310 in the closing direction Q3 about the first swing axis 310 a isfollowed by a swinging movement of the swingable member 330 about thethird swing axis 330 a, which in turn causes a swinging movement of thesecond transport guide member 320 in the closing direction Q4 about thesecond swing axis 320 a toward its first position.

To be more specific, the swingable member 330 swings about the thirdswing axis 330 a relative to the first transport guide member 310, andthe reciprocating part 332 moves in the crosswise directions Y(specifically, along the guide part FLa of the frame FL) toward theother side in the crosswise directions Y (in this example, to the rightin front view). Then, the sliding surface 333 a of the abutting part 333provided at the reciprocating part 332 (specifically, the abutting part333 provided at the reciprocating part 332 by means of the supportingpart 334) is caused to slide along the sliding contact guide part 322 ofthe second transport guide member 320. At this time, the abutting part333 of the reciprocating part 332 which is moving to the other side inthe crosswise directions Y causes the second transport guide member 320to come down by its own weight, by sliding along the sliding contactsurface 322 a which intersects with the locus of movement β. Thereafter,the sliding surface 333 a and the sliding contact guide part 322 losecontact with each other. The second transport guide member 320 at itsfirst position allows the upstream end 320 e to rest on the downstreamend 301 a of the document tray 301 by its own weight, and the firsttransport guide member 310 is closed.

[Remarks on the Present Embodiments]

In the automatic document feeder 300 described in any of the aboveembodiments, the second transport guide member 320 may be positioned atthe first position when the first transport guide member 310 is closed,at the second position where the second transport guide member 320 opensfrom the first position when the first transport guide member 310 isopened, or at the third position where the second transport guide member320 is opened from the second position. Hence, the second transportguide member 320 can be opened and closed freely relative to the firsttransport guide member 310. Eventually, the automatic document feeder300 can facilitate the paper jam clearing operation for a document G andcan enhance the work efficiency.

To be more specific, when the second transport guide member 320 is atthe second position, opening from the first position, an operator canrecognize that he/she can open and close the second transport guidemember 320 and can grip the second transport guide member 320 easily, sothat an operator can easily open the second transport guide member 320.Besides, when the second transport guide member 320 at the secondposition is opened or closed, with the first transport guide member 310open, an operator OP can check without fail whether a document G isjammed at the second transport guide member 320 on the far side of thefirst transport guide member 310 (in this example, in the second sheettransport path 303 c or the reverse sheet transport path 303 b). In thecase where a document G is jammed at the second transport guide member320 on the near side of the first transport guide member 310 (in thisexample, in the first sheet transport path 303 a), an operator OP canremove the document G jammed at the second transport guide member 320 onthe near side of the first transport guide member 310, with the firsttransport guide member 310 being open. Further, in the case where adocument G is jammed at the second transport guide member 320 on the farside of the first transport guide member 310 (in this example, in thesecond sheet transport path 303 c or the reverse sheet transport path303 b), the second transport guide member 320 is opened from the secondposition to the third position, with the first transport guide member310 being open. As a result, an operator OP can easily remove thedocument G jammed at the second transport guide member 320 on the farside of the first transport guide member 310.

In the automatic document feeder 300, the second transport guide member320 is swingable about the second axis P2 (in this example, the secondswing axis 320 a). Hence, if a document G is jammed at the secondtransport guide member 320 on the far side of the first transport guidemember 310, an operator OP can easily conduct a paper jam clearingoperation for removing a document G jammed at the second transport guidemember 320 on the far side of the first transport guide member 310.Moreover, since the swingable member 330 is swingable about the thirdaxis P3 (in this example, the third swing axis 330 a), relative to thefirst transport guide member 310, at a position different from the firstaxis of the first transport guide member 310 (in this example, the firstswing axis 310 a), an operator OP can open and close the secondtransport guide member 320 freely relative to the swingable member 330,and can thereby open and close the second transport guide member 320freely relative to the first transport guide member 310. As a result,the automatic document feeder 300 can facilitate the paper jam clearingoperation for a document G and can enhance the work efficiency.

Furthermore, in the automatic document feeder 300, when the firsttransport guide member 310 is opened or closed, the first transportguide member 310 moves in an opening/closing direction about the firstaxis (in this example, the first swing axis 310 a), followed by aswinging movement of the swingable member 330 about the third axis P3(in this example, the third swing axis 330 a). In synchronization withthe swinging movement of the swingable member 330, the second transportguide member 320 is caused to swing about the second axis P2 (in thisexample, the second swing axis 320 a). Owing to this arrangement, anoperator OP can recognize that the second transport guide member 320 canbe opened and closed and can easily grip the second transport guidemember 320 which has made a swinging movement. Eventually, an operatorOP can open the second transport guide member 320 easily.

In the present embodiments, the second transport guide member 320 isbrought to the second position by the swingable member 330 which swingswith the opening/closing movement of the first transport guide member310. Thus, the second transport guide member 320 can be brought to thesecond position by a simple arrangement.

The second transport guide member 320 and the swingable member 330 maybe detachably connected by a connection member. However, use of aconnection member tends to sacrifice the work efficiency in a paper jamclearing operation for a document G, complicates the structure of theapparatus, and increases the cost for components.

In this regard, the automatic document feeder 300 according to any ofthe present embodiments is arranged to prevent the first transport guidemember 310 and the swingable member 330 from swinging in synchronizationwith the opening/closing movement of the second transport guide member320 about the second swing axis 320 a when the second transport guidemember 320 is opened or closed. This arrangement allows the secondtransport guide member 320 to be opened and closed more freely relativeto the first transport guide member 310 and the swingable member 330,thereby facilitating the paper jam clearing operation for a document Gand enhancing the work efficiency. In addition, the automatic documentfeeder 300 does not require a connection member, thereby simplifying thestructure of the apparatus and reducing the cost for components.

In the present embodiments, the swingable member 330 is provided withthe reciprocating part 332 and the abutting part 333. The secondtransport guide member 320 is provided with the sliding contact guidepart 322 which is arranged to make a sliding contact with the abuttingpart 333 of the swingable member 330 and to lift the second transportguide member 320 about the second axis P2 (in this example, the secondswing axis 320 a) when the reciprocating part 332 of the swingablemember 330 moves. Hence, when the reciprocating part 332 of theswingable member 330 moves in response to the opening movement of thefirst transport guide member 310, the abutting part 333 makes a slidingmovement along the sliding contact guide part 322, thereby lifting thesecond transport guide member 320 in the open direction Q2 about thesecond axis P2 (in this example, the second swing axis 320 a).

As mentioned, the second transport guide member 320 is swingable aboutthe second axis P2 (in this example, the second swing axis 320 a). If anoperator OP closes the second transport guide member 320 in an openstate quite powerfully (namely, if the second transport guide member 320is closed violently), the sliding contact guide part 322 hits theabutting part 333 so violently as to cause the abutting part 333 to bebroken, to come off from the reciprocating part 332, or to be damagedotherwise. Such a trouble is particularly noticeable in the case wherethe first transport guide member 310 and the swingable member 330 areprevented from swinging in synchronization with the opening/closingmovement of the second transport guide member 320 about the second swingaxis 320 a when the second transport guide member 320 is opened orclosed.

In this regard, the swingable member 330 in the present embodiments isfurther provided with the supporting part 334, and the abutting part 333is supported by the reciprocating part 332 by means of the supportingpart 334. This arrangement can prevent the abutting part 333 from beingbroken, coming off from the reciprocating part 332, or being damagedotherwise. The supporting part 334, being flexible, can reduce an impacton the abutting part 333. This arrangement can further prevent theabutting part 333 from being broken, coming off from the reciprocatingpart 332, or being damaged otherwise. These arrangements areparticularly effective in the case where the first transport guidemember 310 and the swingable member 330 are prevented from swinging insynchronization with the opening/closing movement of the secondtransport guide member 320 about the second swing axis 320 a when thesecond transport guide member 320 is opened or closed.

As mentioned, in the state where the first transport guide member 310 isopen, the abutting part 333 of the swingable member 330 is caused toslide along the sliding contact guide part 322 so as to lift the secondtransport guide member 320. During this operation, if the secondtransport guide member 320 is lifted too much (opened too much), atrouble may occur when an operator attempts to close only the secondtransport guide member 320 forcibly. Namely, an excessive load isimposed on the sliding contact guide part 322 of the second transportguide member 320 and the abutting part 333 of the swingable member 330,and breaks the second transport guide member 320 and/or the swingablemember 330.

In this regard, when the first transport guide member 310 is opened, thesliding contact guide part 322 in the present embodiments is arranged tolift the second transport guide member 320 by a predetermined degree inthe open direction Q2 about the second axis P2 (in this example, thesecond swing axis 320 a) to such an extent that an operator canrecognize that the second transport guide member 320 can be opened andclosed. In the state where the first transport guide member 310 is open,this arrangement can effectively prevent an operator OP from closing thesecond transport guide member 320, and hence can avoid an excessive loadon the sliding contact guide part 322 of the second transport guidemember 320 and the abutting part 333 of the swingable member 330.Eventually, the second transport guide member 320 and/or the swingablemember 330 can be effectively protected from breakage.

Further in the present embodiments, the frame FL provided in theautomatic document feeder main body 300 a includes the guide part FLafor guiding the reciprocating part 332 of the swingable member 330 inthe reciprocating directions (in this example, the crosswise directionsY). The reciprocating part 332 of the swingable member 330 is equippedwith the engagement portion 332 a to be engaged with the guide part FLaof the frame FL, so that the engagement portion 332 a of thereciprocating part 332 can be guided in the guide part FLa of the frameFL without fail. Eventually, this arrangement ensures a stablereciprocating movement of the reciprocating part 332 of the swingablemember 330 in association with the opening movement of the firsttransport guide member 310.

Further in the present embodiments, the biasing member 340 is disposedbetween the reciprocating part 332 of the swingable member 330 and theframe FL, and biases the first transport guide member 310 in the opendirection Q1 about the first axis (in this example, the first swing axis310 a). By making use of the reciprocating mechanism of thereciprocating part 332 in the swingable member 330 associated with theopening movement of the first transport guide member 310, a biasingforce of the biasing member 340 can be applied to the first transportguide member 310 in the open direction Q1 about the first axis (in thisexample, the first swing axis 310 a). Eventually, the biasing force ofthe biasing member 340 can be applied to the first transport guidemember 310 by a simple structure.

In the present embodiments, the biasing member 340 is a long,general-purpose coil spring. In the state where the first transportguide member 310 is closed, the biasing member 340 is oriented in thereciprocating directions (in this example, the crosswise directions Y)and arranged between the reciprocating part 332 and the frame FL. Hence,the first transport guide member 310 can be biased, by means of theswingable member 330, in the open direction Q1 about the first axis (inthis example, the first swing axis 310 a), without sacrificing thebiasing capacity of the biasing member 340 when the reciprocating part332 reciprocates in the reciprocating directions (in this example, thecrosswise directions Y).

In the present embodiments, the second transport guide member 320 isarranged to stop at its third position, thereby preventing the secondtransport guide member 320 from making a rotational movement by its ownweight during the paper jam clearing operation for a document G jammedat the second transport guide member 320 on the far side of the firsttransport guide member 310. With this arrangement, it is no longernecessary for an operator to keep gripping the second transport guidemember 320 during the paper jam clearing operation, and an operator caneasily remove a document G jammed at the second transport guide member320 on the far side of the first transport guide member 310. Thisarrangement can further facilitate the paper jam clearing operation fora document G and can further enhance the work efficiency.

In the present embodiments, since the second transport guide member 320is arranged to open and close rotatably at its second position, thesecond transport guide member 320 can be opened and closed at the secondposition by a simple structure.

Regarding the second transport guide member 320, the degree of openingat its second position and the degree of opening at its third positionare different by d1 (angular degree). Similarly, the degree of openingat its second position and the degree of opening of its first positionare different by d2 (angular degree). In the present embodiments, thedifference d1 is greater than the difference d2. This arrangementfacilitates removal of a document G jammed between the first transportguide member 310 and the second transport guide member 320, therebyfurther facilitating the paper jam clearing operation for a document Gand enhancing the work efficiency.

In the present embodiments, an opening d3 between the second transportguide member 320 at its third position and the third transport guidemember 350 is wider than an opening d4 between the second transportguide member 320 at its third position and the first transport guidemember 310 in an open state. This arrangement facilitates removal of adocument G jammed between the second transport guide member 320 and thethird transport guide member 350, thus making it possible to facilitatethe paper jam clearing operation for a document G and to enhance thework efficiency more advantageously.

In the present embodiments, when the second transport guide member 320is opened, the second transport guide member 320 stops at its thirdposition where the center of gravity M2 of the second transport guidemember 320 is on a closed side of the second transport guide member 320relative to an imaginary vertical line γ2 which passes through thesecond axis P2. During the paper jam clearing operation for a document Gjammed at the second transport guide member 320 on the far side of thefirst transport guide member 310, this arrangement can prevent thesecond transport guide member 320 from moving rotationally in theclosing direction by its own weight. With this arrangement, it is nolonger necessary for an operator to keep gripping the second transportguide member 320 during the paper jam clearing operation, thus making itpossible to facilitate the paper jam clearing operation for a document Gjammed at the second transport guide member 320 on the far side of thefirst transport guide member 310 and to enhance the work efficiency moreadvantageously.

In the present embodiments, when the second transport guide member 320is opened, the second transport guide member 320 is limited by the firsttransport guide member 310 and stops at its third position where thecenter of gravity M2 of the second transport guide member 320 is on anopen side of the second transport guide member 320 relative to animaginary vertical line γ2 which passes through the second axis P2.During the paper jam clearing operation for a document G jammed at thesecond transport guide member 320 on the far side of the first transportguide member 310, this arrangement can prevent the second transportguide member 320 from moving rotationally in the opening direction byits own weight. With this arrangement, it is no longer necessary for anoperator to keep gripping the second transport guide member 320 duringthe paper jam clearing operation, thus making it possible to facilitatethe paper jam clearing operation for a document G jammed at the secondtransport guide member 320 on the far side of the first transport guidemember 310 and to enhance the work efficiency more advantageously.Besides, since the second transport guide member 320 stops at its thirdposition by being limited by the first transport guide member 310, anadditional member for stopping the second transport guide member 320 canbe omitted. This arrangement further contributes to a simplifiedstructure and low-cost production.

In the present embodiments, when the first transport guide member 310 isopened, the first transport guide member 310 stops at its first positionwhere the center of gravity M1 of the first transport guide member 310is on a closed side of the first transport guide member 310 relative toan imaginary vertical line γ1 which passes through the first axis P1.During the paper jam clearing operation for a document G jammed at thesecond transport guide member 320 on the near side of the firsttransport guide member 310, this arrangement can prevent the firsttransport guide member 310 from moving rotationally in the closingdirection by its own weight. With this arrangement, it is no longernecessary for an operator no longer needs to keep gripping the firsttransport guide member 310 during the paper jam clearing operation, thusmaking it possible to facilitate the paper jam clearing operation for adocument G jammed at the second transport guide member 320 on the nearside of the first transport guide member 310 and to enhance the workefficiency more advantageously.

In the present embodiments, when the first transport guide member 310 isopened, the first transport guide member 310 stops at its secondposition where the center of gravity M1 of the first transport guidemember 310 is on an open side of the first transport guide member 310relative to an imaginary vertical line γ1 which passes through the firstaxis P1. During the paper jam clearing operation for a document G jammedat the second transport guide member 320 on the near side of the firsttransport guide member 310, this arrangement can prevent the firsttransport guide member 310 from moving rotationally in the openingdirection by its own weight. With this arrangement, it is no longernecessary for an operator to keep gripping the first transport guidemember 310 during the paper jam clearing operation, thus making itpossible to facilitate the paper jam clearing operation for a document Gjammed at the second transport guide member 320 on the near side of thefirst transport guide member 310 and to enhance the work efficiency moreadvantageously.

In the present embodiments, the recess 325 is provided at an end of thesecond transport guide member 320 (the upstream end 320 e in thetransport direction Y1) opposite to the swing fulcrum of the secondtransport guide member 320 (the second axis P2). Hence, an operator OPcan insert his/her fingers in the recess 325 of the second transportguide member 320, and can thereby easily open the second transport guidemember 320.

In the present embodiments, the recess 325 in the second transport guidemember 320 is positioned closer to an operation side X1 relative to thecenter in the width directions X. This arrangement improves operabilityin the opening operation of the second transport guide member 320 by anoperator OP.

In the present embodiments, the automatic document feeder 300 isequipped with the interlock detection switch 370 and the activating part323. The interlock detection switch 370 is provided in either of thefirst transport guide member 310 or the second transport guide member320 (in this example, the first transport guide member 310), and theactivating part 323 is provided in the other transport guide member (inthis example, the second transport guide member 320). The interlockdetection switch 370 and the activating part 323 are positioned suchthat, in the state where the first transport guide member 310 is closed,the interlock detection switch 370 is turned on by the activating part323.

Incidentally, the interlock detection switch 370 should be turned offwhen the first transport guide member 310 and the second transport guidemember 320 are both open. However, if the first axis of the firsttransport guide member 310 (in this example, the first swing axis 310 a)and the second axis P2 of the second transport guide member 320 (in thisexample, the second swing axis 320 a) are disposed at the same positionor a substantially same position, when the second transport guide member320 is opened after the first transport guide member 310 is opened, theactivating part 323 turns on the interlock detection switch 370, whichcancels the prohibition of the action of the apparatus (in other words,permits the action of the apparatus). This unintended actiondeteriorates the safety in the state where the first transport guidemember 310 and the second transport guide member 320 are both open.

In this regard, the first axis of the first transport guide member 310(in this example, the first swing axis 310 a) and the second axis P2 ofthe second transport guide member 320 (in this example, the second swingaxis 320 a) are disposed at different positions from each other in thepresent embodiments. Even when the second transport guide member 320 isopened after the first transport guide member 310 is opened, theinterlock detection switch 370 and the activating part 323 can bepositioned as shown in FIG. 22 such that the interlock detection switch370 is not turned on by the activating part 323, with the firsttransport guide member 310 and the second transport guide member 320being both open. This arrangement can prevent the interlock detectionswitch 370 from being turned on by the activating part 323 in anunintended situation. Eventually, while the first transport guide member310 and the second transport guide member 320 are both open, it ispossible to keep prohibiting the action of the apparatus, and thereby toeffectively prevent deterioration in the safety in the state where thefirst transport guide member 310 and the second transport guide member320 are both open.

In the present embodiments, the second transport guide member 320 isarranged on the rotation axis of a roller for transporting a document G.Hence, the rotation axis of an existing roller can be utilized as aswing axis serving as the second axis P2 of the second transport guidemember 320. There is no need for an additional swing axis to serve asthe second axis P2 of the second transport guide member 320, and theapparatus can be obtained in a reduced size at a reduced cost. Besides,the second transport guide member 320 is detachably arranged on therotation axis of a roller for transporting a document G, which enhancesthe efficiency in maintenance work.

Regarding the pair of registration rollers 304 a, 304 b in the presentembodiments, the first registration roller 304 a is provided in thefirst transport guide member 310, and the second registration roller 304b is provided in the automatic document feeder main body 300 a. Thesecond transport guide member 320 is swingable about the axis ofrotation of the second registration roller 304 b (the second swing axis320 a). Hence, the rotation axis of an existing roller can be utilizedas a swing axis serving as the second axis P2 of the second transportguide member 320, and the automatic document feeder 300 can be obtainedin a reduced size at a reduced cost.

The sheet transport guide section 306 in the present embodiments isarranged to reverse a document G from one side to the other. Even if areversed document G is jammed at the second transport guide member 320on the far side of the first transport guide member 310, thisarrangement facilitates the paper jam clearing operation for a documentG at the second transport guide member 320 on the far side of the firsttransport guide member 310.

The automatic document feeder 300 in the present embodiments includesthe reverse sheet transport path 303 b, the discharge transport part307, and the third transport guide member 350. The third transport guidemember 350 constitutes the second sheet transport path 303 c between thethird transport guide member 350 and the second transport guide member320, and the second sheet transport path 303 c allows passage of thedocument G which is transported backward at the discharge transport part307. In this arrangement, a document G fed from the first sheettransport path 303 a into the reverse sheet transport path 303 b isreversed from one side to the other in the reverse sheet transport path303 b, and is transported backward at the discharge transport part 307during the process of discharge. Even if the reversed document G isjammed in the second sheet transport path 303 c, this arrangementfacilitates the paper jam clearing operation for a document G at thethird transport guide member 350.

In the present embodiments, the branching member 308 is provided withthrough-windows 308 c, each of which penetrates from the second sheettransport path 303 c side to the reverse sheet transport path 303 bside. The through-windows 308 c allows an operator OP to see the stateof a document G in the reverse sheet transport path 303 b. Thus, anoperator OP can check the state of the document G, including thepresence or absence of the document G, in the reverse sheet transportpath 303 b.

In the present embodiments, the plurality of through-windows 308 c-308 care arranged side by side in the width directions X. Thesethrough-windows 308 c allow an operator OP to check a document G jammedin the reverse sheet transport path 303 b, entirely across the widthdirections X.

Other Embodiments

The sheet transport apparatus according to the present embodiments isapplied to the automatic document feeder 300, but should not be limitedthereto. For example, the sheet transport apparatus according to thepresent embodiments may also be applied to the image forming apparatusmain body 110 and may transport a recording sheet P as a sheet.

The present invention should not be limited to the embodiments describedabove, but may also be implemented in other various manners. Therefore,the above-described embodiments are considered in all respects asillustrative and not restrictive. The scope of the invention isindicated by the appended claims rather than the foregoing description.All variations and modifications falling within the equivalency range ofthe appended claims are intended to be embraced therein.

What is claimed is:
 1. A sheet transport apparatus equipped with a sheettransport guide section for guiding a sheet to be transported, the sheettransport guide section comprising: a first transport guide member whichis swingable about a first axis extending in a width direction of thesheet, the width direction being orthogonal or substantially orthogonalto a sheet transport direction; and a second transport guide memberwhich is swingable about a second axis extending in the width directionand which forms a sheet transport path for allowing passage of the sheetbetween the second transport guide member and the first transport guidemember, wherein the second transport guide member is arranged at a firstposition when the first transport guide member is closed, at a secondposition where the second transport guide member is opened from thefirst position when the first transport guide member is opened, or at athird position where the second transport guide member is opened fromthe second position.
 2. The sheet transport apparatus according to claim1, wherein the second transport guide member stops at the thirdposition.
 3. The sheet transport apparatus according to claim 2, whereina difference between a degree of opening of the second transport guidemember at the second position and a degree of opening of the secondtransport guide member at the third position is greater than adifference between a degree of opening of the second transport guidemember at the second position and a degree of opening of the secondtransport guide member at the first position.
 4. The sheet transportapparatus according to claim 2, further comprising a third transportguide member for guiding the sheet to be transported between the thirdtransport guide member and the second transport guide member, wherein anopening between the second transport guide member at the third positionand the third transport guide member is wider than an opening betweenthe second transport guide member at the third position and the firsttransport guide member in an open state.
 5. The sheet transportapparatus according to claim 2, wherein, when the second transport guidemember is opened, the second transport guide member stops at the thirdposition where a center of gravity of the second transport guide memberis on a closed side of the second transport guide member relative to animaginary vertical line which passes through the second axis.
 6. Thesheet transport apparatus according to claim 2, wherein, when the secondtransport guide member is opened, the second transport guide member islimited by the first transport guide member and stops at the thirdposition where a center of gravity of the second transport guide memberis on an open side of the second transport guide member relative to animaginary vertical line which passes through the second axis.
 7. Thesheet transport apparatus according to claim 1, wherein, when the firsttransport guide member is opened, the first transport guide member stopsat a first position thereof where a center of gravity of the firsttransport guide member is on a closed side of the first transport guidemember relative to an imaginary vertical line which passes through thefirst axis.
 8. The sheet transport apparatus according to claim 1,wherein, when the first transport guide member is opened, the firsttransport guide member stops at a second position thereof where a centerof gravity of the first transport guide member is on an open side of thefirst transport guide member relative to an imaginary vertical linewhich passes through the first axis.
 9. The sheet transport apparatusaccording to claim 1, wherein a recess is provided at an end of thesecond transport guide member opposite to a swing fulcrum of the secondtransport guide member.
 10. The sheet transport apparatus according toclaim 1, further comprising an interlock detection switch forprohibiting an action of the apparatus, and an activating part foractivating the interlock detection switch, wherein the interlockdetection switch is provided in either of the first transport guidemember or the second transport guide member, and the activating part isprovided in the other transport guide member, wherein the interlockdetection switch and the activating part are positioned such that, in astate where the first transport guide member is closed, the interlockdetection switch is turned on by the activating part, and wherein thefirst axis in the first transport guide member and the second axis inthe second transport guide member are provided at different positionsfrom each other.
 11. An image forming apparatus comprising the sheettransport apparatus according to claim
 1. 12. A sheet transportapparatus equipped with a sheet transport guide section for guiding asheet to be transported, the sheet transport guide section comprising: afirst transport guide member which is swingable about a first axisextending in a width direction of the sheet, the width direction beingorthogonal or substantially orthogonal to a sheet transport direction; asecond transport guide member which is swingable about a second axisextending in the width direction and which forms a sheet transport pathfor allowing passage of the sheet between the second transport guidemember and the first transport guide member; and a swingable memberwhich is swingable about a third axis extending in the width direction,relative to the first transport guide member, at a different positionfrom the first axis of the first transport guide member, wherein, whenthe first transport guide member is opened or closed, the firsttransport guide member moves in an opening or closing direction aboutthe first axis, followed by a swinging movement of the swingable memberabout the third axis, and the second transport guide member is arrangedto swing about the second axis in synchronization with the swingingmovement of the swingable member.
 13. The sheet transport apparatusaccording to claim 12, wherein, even when the second transport guidemember is opened or closed, the first transport guide member and theswingable member are arranged not to swing in synchronization with anopening or closing movement of the second transport guide member aboutthe second swing axis.
 14. The sheet transport apparatus according toclaim 12, wherein the swingable member comprises: a reciprocating partwhich makes a reciprocating movement in reciprocating directions whichare orthogonal or substantially orthogonal to the width direction whenthe swingable member swings about the third axis in synchronization withan opening movement of the first transport guide member; and an abuttingpart provided on the reciprocating part and arranged to abut on thesecond transport guide member, and wherein the second transport guidemember comprises a sliding contact guide part which is arranged to comeinto sliding contact with the abutting part of the swingable member whenthe reciprocating part of the swingable member moves, and thereby tocause the second transport guide member to be lifted about the secondaxis.
 15. The sheet transport apparatus according to claim 14, whereinthe swingable member further comprises a supporting part, and whereinthe abutting part is supported by the reciprocating part by means of thesupporting part.
 16. The sheet transport apparatus according to claim14, further comprising a frame provided in a main body of the sheettransport apparatus, wherein the frame is provided with a guide part forguiding the reciprocating part of the swingable member in thereciprocating directions, and wherein the reciprocating part of theswingable member is provided with an engagement portion to be engagedwith the guide part of the frame.
 17. The sheet transport apparatusaccording to claim 16, further comprising a biasing member which isprovided between the reciprocating part of the swingable member and theframe, and which biases, by means of the swingable member, the firsttransport guide member in an open direction about the first axis. 18.The sheet transport apparatus according to claim 12, wherein the secondtransport guide member is arranged at a first position when the firsttransport guide member is closed, at a second position where the secondtransport guide member is opened from the first position when the firsttransport guide member is opened, or at a third position where thesecond transport guide member is opened from the second position. 19.The sheet transport apparatus according to claim 18, wherein the secondtransport guide member stops at the third position.
 20. The sheettransport apparatus according to claim 19, wherein a difference betweena degree of opening of the second transport guide member at the secondposition and a degree of opening of the second transport guide member atthe third position is greater than a difference between a degree ofopening of the second transport guide member at the second position anda degree of opening of the second transport guide member at the firstposition.
 21. The sheet transport apparatus according to claim 19,further comprising a third transport guide member for guiding the sheetto be transported between the third transport guide member and thesecond transport guide member, wherein an opening between the secondtransport guide member at the third position and the third transportguide member is wider than an opening between the second transport guidemember at the third position and the first transport guide member in anopen state.
 22. The sheet transport apparatus according to claim 19,wherein, when the second transport guide member is opened, the secondtransport guide member stops at the third position where a center ofgravity of the second transport guide member is on a closed side of thesecond transport guide member relative to an imaginary vertical linewhich passes through the second axis.
 23. The sheet transport apparatusaccording to claim 19, wherein, when the second transport guide memberis opened, the second transport guide member is limited by the firsttransport guide member and stops at the third position where a center ofgravity of the second transport guide member is on an open side of thesecond transport guide member relative to an imaginary vertical linewhich passes through the second axis.
 24. The sheet transport apparatusaccording to claim 12, wherein, when the first transport guide member isopened, the first transport guide member stops at a first positionthereof where a center of gravity of the first transport guide member ison a closed side of the first transport guide member relative to animaginary vertical line which passes through the first axis.
 25. Thesheet transport apparatus according to claim 12, wherein, when the firsttransport guide member is opened, the first transport guide member stopsat a second position thereof where a center of gravity of the firsttransport guide member is on an open side of the first transport guidemember relative to an imaginary vertical line which passes through thefirst axis.
 26. The sheet transport apparatus according to claim 12,wherein a recess is provided at an end of the second transport guidemember opposite to a swing fulcrum of the second transport guide member.27. The sheet transport apparatus according to claim 12, furthercomprising an interlock detection switch for prohibiting an action ofthe apparatus, and an activating part for activating the interlockdetection switch, wherein the interlock detection switch is provided ineither of the first transport guide member or the second transport guidemember, and the activating part is provided in the other transport guidemember, wherein the interlock detection switch and the activating partare positioned such that, in a state where the first transport guidemember is closed, the interlock detection switch is turned on by theactivating part, and wherein the first axis in the first transport guidemember and the second axis in the second transport guide member areprovided at different positions from each other.
 28. An image formingapparatus comprising the sheet transport apparatus according to claim12.